Oil and Gas Resource Development Potential
Eastern Valle Vidal Unit
By
Brian S. Brister, Gretchen K. Hoffman and Thomas W. Engler
New Mexico Bureau of Geology and Mineral Resources, New Mexico Tech
Socorro, New Mexico 87801
Open-file Report 491
2005
Oil and Gas Resource Development Potential
Eastern Valle Vidal Unit
A 20-year Reasonable Foreseeable Development Scenario
(RFDS)
Carson National Forest
Investigators:
Dr. Brian S. Brister, C. P. G. (AAPG #5826), Petroleum Geologist, New Mexico
Bureau of Geology and Mineral Resources, a division of New Mexico Institute of
Mining and Technology, 801 Leroy Place, Socorro, NM 87801
Gretchen K. Hoffman, Senior Coal Geologist (project database coordinator) New
Mexico Bureau of Geology and Mineral Resources, a division of New Mexico
Institute of Mining and Technology
Dr. Thomas W. Engler, P. E. (NM #12317), Assistant Professor and Department
Chair, Petroleum and Chemical Engineering Department, New Mexico Institute of
Mining and Technology
Assisted by:
Christopher Haley, Johanna Abney, and Nick Trvdy, students at New Mexico
Institute of Mining and Technology
Report submitted July 9, 2004
Report submitted to:
Diane Tafoya, RFDS Project Coordinator and New Mexico Zone Geologist
Forest Service
Southwestern Region
333 Broadway, SE
Albuquerque, NM 87102
x
Table of Contents
Disclaimers
Executive summary
List of Abbreviations and Acronyms
iv
v
viii
Chapter 1 Introduction
1.1 Description and location of eastern Valle Vidal Unit
1.2 Purpose and scope of RFDS
1
1
3
Chapter 2 Methods
2.1 Estimation of resource potential and potential for development
2.2 Production analysis and estimation
2.3 Prediction of surface occupancy and disturbance
2.4 Operator survey and processing
2.5 GIS project platform and databases
5
5
5
6
6
6
Chapter 3 Background Geology
3.1 Geologic setting
3.2 Structural geology
3.3 Stratigraphic summary
8
8
12
15
Chapter 4 Estimation of Resource Potential and Development
4.1 Oil and gas exploration history
4.2 Ranking potential for occurrence
4.3 Ranking potential for development
4.4 Vermejo-Raton coalbed methane play
4.5 Pierre-Dakota oil and gas play
4.6 Pennsylvanian-Permian gas play
25
25
26
27
29
42
45
Chapter 5 Production Analysis and Estimation
5.1 General characteristics
5.2 Analysis of single well performance
5.3 Multi-well production response
5.4 Coalbed methane modeling
5.5 Summary
47
47
55
58
59
60
Chapter 6 Surface Occupancy and Disturbance
6.1 Approach
6.2 Surface well locations
6.3 Lease infrastructure
6.4 Footprint of drilling and production operations
62
62
65
65
66
Chapter 7 Responses to Operator Survey
7.1 Summary of responses
7.2 Implications of responses to RFDS
67
67
69
ii
Chapter 8 Impacts of Future Technology
8.1 Technology impacts on the RFDS
8.2 Directional and horizontal drilling
8.3 Completion technology
8.4 Produced water treatment and filtration
70
70
70
71
72
Chapter 9 Conclusions: Reasonable Foreseeable Development Scenario 74
9.1 Potential for occurrence
74
9.2 Potential for development
74
9.3 Drilling activity and surface use forecast
75
References cited
76
Appendices
Appendix 1 Industry Survey of Development in San Juan Basin
Appendix 2 Raton Basin Bibliography
Databases on accompanying CD-ROM
GIS project
Oil and gas well database
Raton coal mine database
iii
Carson National Forest Disclaimer
The views and conclusions contained in this document are those of the authors
and should not be interpreted as representing the opinions or policies of the U.S.
Government. Mention of trade names or commercial products does not
constitute their endorsement by the U.S. Government.
New Mexico Institute of Mining and Technology Disclaimer
The views and conclusions contained in this document are those of the authors
and should not be interpreted as representing the opinions or policies of the New
Mexico Institute of Mining and Technology. Mention of trade names or
commercial products does not constitute their endorsement by the New Mexico
Institute of Mining and Technology.
Authors’ Disclaimer
The views and conclusions contained in this document are derived from
observations and interpretations of public and other sources of information. The
authors have applied their best efforts to utilize scientific methods to arrive at
objective conclusions. The authors shall not be held liable for any misinterpretation or misapplication of the conclusions presented herein.
iv
Oil and Gas Resource Development Potential, Eastern Valle Vidal Unit
A 20-year Reasonable Foreseeable Development Scenario (RFDS)
Carson National Forest
Executive Summary
The Valle Vidal Unit of the Carson National Forest is located in the Raton Basin,
a geologic basin in New Mexico and Colorado that is becoming increasingly
important in providing the nation with natural gas. The petroleum industry has
expressed an interest in leasing within the eastern part of the Unit, an area of
approximately 40,000 acres of the 100,000 total acres. The Reasonable
Foreseeable Development Scenario (RFDS) is a planning tool. It provides a
reasonable estimate of what oil and gas exploration and development activities
might be proposed, should a decision be made to lease the area. Under this
scenario, the RFDS projects what activities might be conducted by a mineral
lessee under current and reasonably foreseeable regulatory conditions and
industry interest. The RFDS is a 20-year forward-looking estimation of oil and
gas exploration and development that is exclusive of other concerns that might
compete for use of land in a multiple-use scenario. As such, it is information
about one resource, with a projection of that resource as developed in a
reasonable foreseeable manner. This information forms a “knowledge baseline”
for the Carson National Forest to consider in any subsequent analyses to
examine leasing or development of the resource. The RFDS can be considered
by the Carson National Forest if building alternative scenarios of the potential
extent and conditions of oil and gas leasing and operations.
The overall potential for occurrence of oil and gas resources in the eastern
Valle Vidal Unit is high. This rank is based on geologic conditions predicted to be
present at the site relative to adjacent lands that are being actively and
economically developed. The primary play of interest is the widespread, shallow
(less than 2000 ft deep) coalbed methane and low permeability sandstone
natural gas play associated with the Vermejo and Raton Formations. The entire
eastern Valle Vidal Unit is underlain by these formations. The coal beds in these
formations are assumed to be minimally thermally mature and capable of being
economically developed on 160 acre per well spacing. Certainty in this
assumption decreases southward over the eastern Valle Vidal Unit due to lack of
direct data in the southern part of the Unit. This assumption could be confirmed
by core drilling a minimal number of wells, testing the cored coal beds for
production potential. Parts of the area (an estimated 6080 acres) could be
excluded from being potential for coalbed methane production due to the
presence of fractured igneous dikes that could cause excessive water production
in nearby wells. Confirming this hypothesis would require drilling, completing,
and testing one or more wells in the affected acreage.
v
Another high potential occurrence play is the fractured “shale” blanket-type
Pierre-Dakota play that also has slight possibility of conventional reservoir traps
in the Dakota Sandstone. The fractured shale play currently has a poor
economic outlook in the short term and is not being pursued adjacent to the
eastern Valle Vidal Unit, but it could become significant in the 20-year life of this
scenario. A third play, based on postulated presence and source rock potential
of the Pennsylvanian Sandia Formation, is assigned a low potential due to
uncertainty and lack of positive indicators such as related oil or gas shows
nearby.
The potential for development of oil and gas resources in the eastern Valle
Vidal Unit is high. If allowed to lease the eastern Valle Vidal Unit, oil and gas
operators will be primarily interested in the immediate economic benefit of
developing the shallow coalbed methane resources throughout the Unit.
Coalbed methane plays benefit from dewatering coal over a large area and it is
probable that operators will require large contiguous blocks of acreage in order to
operate most efficiently and economically.
Development would likely proceed from an initial phase of exploratory drilling
and gas-in-place evaluation at 5 to10 sites spread across the area to evaluate
geologic and economic conditions. A second phase would focus on bringing in
the proper infrastructure to produce the area as a whole. This would include a
pipeline to deliver gas to market and might include electric power. Right-of-way
availability and access to pipeline interconnects is a locally sensitive subject that
would require negotiation and pose unknown financial considerations to be borne
on the part of lessees; thus, pipeline economics were not considered in the
RFDS. It is estimated that at least four deep wells would be required for
subsurface disposal of produced water in approved saline aquifers. Under this
scenario, a third phase would involve drilling every allowed surface location on
160 acre spacing with vertical wells. A fourth phase might involve drilling
problematic locations using deviated (not horizontal) wellbores if economics
prove to be sufficient. Deep targets would be tested as a side benefit of drilling
water disposal wells and do not require additional locations in this scenario.
Development of the coalbed methane resource is not likely to require
reflection seismic data. Evaluation of deeper plays would benefit from such data.
Operators in the region have expressed interest in 3-D seismic data with
lines/cross-lines spaced closer than ¼ mile. No evidence of existence of 3-D
seismic data or current acquisition activity was found in the vicinity. It is proposed
that once coalbed methane related lease roads were constructed, seismic
operations could take place on the road grid.
Over the 20-year life of the RFDS, it is predicted that between 195 and 254
vertical or slightly deviated wellbores could be drilled on 191 to 250 surface
locations (well pads) based on current and foreseeable State of New Mexicoregulated well density of 160 acres per well. Four of those wells would be drilled
vi
as water disposal wells/deep tests and could be placed on an existing location
with a shallow coalbed methane well. If increased-density spacing of 80 acres
per well were approved by the State of New Mexico during the term of the RFDS,
then the predicted number of wellbores could double to 390 to 508. Associated
80-acre spaced well pads would number 382 to 500. At present, there is no
justifiable need to increase density to 80 acres per well, but necessary data could
become available over time, derived from 160 acre-spaced wells. The coalbed
methane reservoir conditions are not conducive to horizontal drilling due to
complicating factors including the difficulty of artificially lifting water, thin
discontinuous beds within a thick gross interval, shallow depth, and poor
economics. Deviated (not horizontal) drilling methods could help to reduce the
surface impacts of development by allowing optional nonstandard locations for
construction of well pads, such as locating multiple wellheads on a single pad.
The area of disturbance for each coalbed methane well location need not be
large because the shallow depth and minimal required equipment allow for small
well pads. Typical surface disturbance associated with current producing well
pads in the Raton Basin is about 0.5 acres whereas well pads elsewhere in New
Mexico are normally about 2 acres in size. Roadways and right-of-ways add an
additional acre of disturbance per 160-acre-spaced well pad. Water disposal and
compression facilities add an additional 15 acres. It is estimated that full
development as a single lease at 160 acres spacing per well will require between
396 and 777 acres of disturbance over the entire unit depending upon well pad
area required. This doubles if 80-acre spacing per well development becomes
an option. Innovative and environmentally responsible development practices
are encouraged by the authors to reduce impacts on alternative land uses while
promoting maximum economic benefit. Flexibility in locating wells within 160
acre spacing units will promote more effective reservoir drainage and may
potentially mitigate other impacts.
There is no official government township-grid survey in the eastern Valle Vidal
Unit. This information is critical for assigning lease ownership and locating wells.
It is recommended that a survey be performed on the ground prior to mineral
leasing if the lands are to be offered for lease.
vii
x
List of Abbreviations and Acronyms
AAPG
ACCESS
AIME
ARCGIS
BBL/bbl
Bw
mBw
CBM
CIM
C. P. G.
DRG
EIS
EPA
EUR
ft
GIS
GOTECH
Gp
GRI
ISC
km
m
NM
NMBGMR
NMIMT
NMOCD
ONGARD
P. E.
RFDS
American Association of Petroleum Geologists
a relational database computer program, product of Microsoft
American Institute of Mining, Metallurgical and Petroleum Engineers
a GIS computer program, product of Earth Science Resources Inc.
barrels, a volumetric term for water, equals 42 gallons
barrels of water
thousand barrels of water
coalbed methane
Canadian Institute of Mining, Metallurgical, and Petroleum Engineers
Certified Petroleum Geologist
Digital Raster Graphic; a digital image product
Environmental Impact Statement
U. S. Environmental Protection Agency
estimated ultimate recovery
feet, foot
geographic information system
website by New Mexico Petroleum Recovery Research Center
gas in place
Gas Research Institute
Interstate Stream Commission
kilometer (s)
meter (s)
New Mexico
New Mexico Bureau of Geology and Mineral Resources
New Mexico Institute of Mining and Technology
New Mexico Oil Conservation Division
Well database by New Mexico Oil Conservation Division
Professional Engineer
reasonable foreseeable development scenario
RGIS
Ro
New Mexico Resource Geographic Information System.
vitrinite reflectance; indicator of source rock thermal maturity
scf
mscf/mcf
mmscf
Bscf/Bcf
Tscf/Tcf
S. P. E.
TDS
U. S.
VPR
WGR
Wp
standard cubic feet, a volumetric term for natural gas
thousand cubic feet, standard volumetric unit for market trading
million cubic feet
billion cubic feet
trillion cubic feet
Society of Petroleum Engineers
total dissolved solids, a water quality measurement
United State of America
Vermejo Park Ranch, lease name applied to development areas
water to gas ratio; water:gas
water in place
viii
Chapter 1 Introduction
1.1 Description and location of eastern Valle Vidal Unit
The Valle Vidal Unit is located in the Raton Basin, a geologic basin in New
Mexico and Colorado that is becoming increasingly important in providing the
nation with natural gas. The Valle Vidal Unit became a part of the National
Forest System in 1982 through donation by Pennzoil Corporation. The donation
included both the surface and oil and gas mineral estate (including coalbed
methane) according to the Carson National Forest. Coal mineral rights are
owned by Pittsburg & Midway Coal Mining Company (a division of Chevron).
The eastern Valle Vidal Unit, the subject of study for this Reasonable
Foreseeable Development Scenario (RFDS), encompasses an area of
approximately 40,000 acres of the 100,000 total acres comprising the Valle Vidal
Unit. The eastern Valle Vidal Unit includes all the land within the National Forest
boundary east of a geologic feature called The Rock Wall as depicted in Figure
1.1. The privately owned Vermejo Park Ranch lies to the north, northeast, and
south of the eastern Valle Vidal Unit. The Elliot Barker State Wildlife Area, and
privately owned Philmont Scout Ranch and Ponil Ranch lie to the southeast and
east.
The Valle Vidal Unit and adjacent properties are subdivided from the Maxwell
Land Grant of 1841 (confirmed by the United States in 1887) that includes
roughly three-fifths of Colfax County (Pettit, 1966). Landowners within the
Maxwell Land Grant have established property boundaries using the metes-andbounds survey method. There is no official governmental survey available for the
land grant that subdivides it into townships based on the New Mexico principal
meridian. A few maps in the public domain show township grids based on
extrapolation from outside the land grant boundaries, but this is done roughly and
inconsistently between maps.
Maps for this report include an unofficial land grid system created from two
sources: an unofficial survey extrapolation of townships from the western edge of
the land grid used by the National Forest Service, and an unofficial survey
extrapolation of townships from the eastern edge of the land grant supplied by
the New Mexico Oil Conservation Division that appears to be consistent with well
locations on the Vermejo Park Ranch. In general, there is an approximate one
mile adjustment at the boundary line between the two surveys, the boundary
being the National Forest Boundary as provided by the Carson National Forest.
It is recommended that an official township-section grid survey be performed
prior to any mineral leasing of the Valle Vidal Unit. The conclusions of the RFDS
will not change significantly by a resurvey because this study is based on general
areas of development rather than on specific well locations.
x
1
Figure 1.1 Index map showing the eastern Valle Vidal Unit, Carson National Forest and approximate boundaries with adjacent private and state
owned lands in Colfax County, New Mexico. Map base reproduced from Carson National Forest (1999).
2
1.2 Purpose and scope of RFDS
The Valle Vidal Unit is currently being managed for multiple uses with special
wildlife management emphasis. There are no oil and gas leases or producing
wells on the Unit. Carson National Forest Resource Management Plan (1986) is
silent in regards to the oil and gas resources. Presently, coalbed methane
production operations are being conducted on the Vermejo Park Ranch, which
lies adjacent to the eastern Valle Vidal Unit. The Carson National Forest
contracted with the New Mexico Bureau of Geology and Mineral Resources to
produce the Reasonable Foreseeable Development Scenario (RFDS) after the
Forest received petroleum industry requests to make the Valle Vidal Unit
available to leasing for similar activities.
The Reasonable Foreseeable Development Scenario (RFDS) provides a
reasonable estimate of what oil and gas exploration and development activities
might be proposed and/or conducted by a mineral lessee under current and
reasonably foreseeable regulatory conditions. The RFDS, with an effective
beginning date of June 1, 2004, is a 20-year forward-looking estimation of oil and
gas exploration and development that is exclusive of other concerns that might
compete for use of land in a multiple-use scenario. Subsequent to this report,
the Carson National Forest may use the document to inform further analyses,
which would consider the impacts of the activities described by the RFDS.
The approach taken by the RFDS team involves three steps:
1) Study and understand the geological factors for hydrocarbon generation,
migration and accumulation. Predict potential for oil and gas reservoirs.
Identify likely locations of reservoirs where possible.
2) Develop scenarios that describe the conditions and technology necessary
to explore for, and access, the predicted oil and gas reservoirs. This step
requires an estimation of how technology may evolve in a twenty-year
time frame.
3) Estimate the type and amount of surface occupancy and disturbance
required to develop the reservoirs.
There are currently no oil and gas related activities being conducted on the
eastern Valle Vidal Unit. The RFDS is based in part on study of an adjacent
producing property and prediction of geological conditions conducive to oil and
gas resources at the Unit. The RFDS includes an analysis of production from
nearby and similar coalbed methane fields as an example of what might be
expected to occur at the Unit if geological conditions are similar. The RFDS and
its authors cannot authorize or endorse oil and gas related activities on any
property, nor does it warrant that any production will actually take place, or be
economic within, the Unit should leases become available. Instead, it merely
predicts what might occur if leasing and subsequent activity were allowed. The
scope of work for the RFDS does not include evaluation of the various potential
environmental impacts of predicted activity, of aquifer characteristics or impacts
3
thereon, or economic or social analysis of predicted activity, production and
possible impacts thereon.
4
Chapter 2 Methods
2.1 Estimation of resource potential and potential for development
The resource potential of the eastern Valle Vidal Unit was estimated based on
analyses of oil and gas plays using a petroleum system approach. An extensive
body of literature was reviewed in order to evaluate and document the existence
of source rock, thermal maturation, reservoir strata possessing permeability
and/or porosity, potential migration pathways, and traps for each play. The
method and timing of development of each play were determined based upon the
current and possible future regulatory and economic climate, and upon current
industry best practices in similar plays in the Rocky Mountain region. Each play
type is ranked as to its potential for occurrence and development during the 20year life of the RFDS. Discussions can be found in Chapter 4 of this report.
2.2 Production analysis and estimation
The objectives of production analysis are to: (1) analyze current well
performance and determine, if possible, the estimated ultimate recovery (EUR)
and other production characteristics of the Raton Basin coalbed methane play
that is currently being developed adjacent to the Valle Vidal Unit, and (2) to
identify any interference, if there is evidence that interference occurs, in the
production response between wells and thus qualitatively determine drainage
area.
The scope of the study consisted of analyzing and comparing historical gas
and water production from different producing regions within the New Mexico
portion of the Raton Basin; and then narrowing the focus of the analysis to
individual well performance of strategic regions in proximity to the Valle Vidal
Unit. All production data through May 2003 was obtained from public domain
data in the New Mexico Oil Conservation Division’s ONGARD data set available
from the New Mexico Petroleum Recovery Research Center GOTECH web site
at http://octane.nmt.edu/
Well production data analysis utilized conventional decline and log-log type
curve matching techniques to estimate recovery and drainage area. The unique
behavior of coals complicates both the analysis and the interpretation. Therefore,
identification of various production responses was undertaken to differentiate
between coalbed methane response and conventional (low-permeability)
behavior. Subsequently, wells that exhibited conventional production decline
were analyzed for reservoir/production properties. Detailed discussion of the
findings from this work can be found in Chapter 5 of this report.
5
2.3 Prediction of surface occupancy and disturbance
Prediction of surface occupancy (Chapter 6) was based upon an estimate of the
number of viable subsurface reservoir cells. Once the number of subsurface
reservoir cells was established, two scenarios for surface occupancy and
disturbance were derived. The first is based on regulations applied in the
Jicarilla District of the Carson National Forest. The second is based on common
industry practices in the vicinity of the Valle Vidal Unit. It also considered how
much of this activity could reasonably be expected to occur in the twenty-year life
of the RFDS.
2.4 Operator survey and processing
In order to test base assumptions of the RFDS analyses, a group of oil and gas
operators was consulted through a concise and confidential survey. The direct
benefit was to tap into the wealth of experience available and obtain currently
perceived development strategy for their properties. The industry survey was
distributed to all operators of record in the Raton Basin in both New Mexico and
Colorado (total of eight). In addition, the survey was made available to the New
Mexico Oil and Gas Association and Colorado Oil and Gas Association for
distribution to interested members. Operators were given thirty days to respond
to the survey. An example of the survey including cover letter is included as
Appendix 1.
Chapter 7 contains a summary of the results. These results were compared
to our independent analysis, and for any discrepancies identified, further
investigation was done to develop an explanation for these differences. The
number of returned responses totaled four, which included three from the Raton
Basin Operators and one non-Raton Basin response. This response rate seems
low unless one considers that the only current operator in the New Mexico part of
the Raton Basin has a virtual monopoly through mineral ownership of much of
the potential acreage in the basin and controls the only pipeline, perhaps
discouraging other operators from having an interest in participating.
2.5 GIS project platform and databases
Data sources utilized and assembled for this RFDS were public domain
resources. Examples are well-specific data compiled by the New Mexico’s Oil
Conservation Division and Bureau of Geology and Mineral Resources, and
geographic information made available by the Carson National Forest. Data from
oil and gas wells and coal mine information for Colfax County were entered into
Microsoft ACCESS databases (see accompanying CD-ROM). The public
domain data was formatted to be accessed and displayed using the ARCGIS
6
platform. This software platform was chosen because it is widely utilized by landuse professionals and it accepts and integrates data that was acquired in a
variety of formats and projection methods. The purpose of the GIS project was to
provide all contractors of the EIS with a common platform early in the process of
work.
Data that was collected and integrated into the ARCGIS project include:
•
Well and mine location, drilling, testing and completion data
compiled from the New Mexico Bureau of Geology and Mineral
Resources (NMBGMR) petroleum records and coal data libraries.
•
Surface geologic mapping information compiled from the digital and
published1:500,000 scale maps by the NMBGMR.
•
The State of New Mexico’s ONGARD well production database
maintained by the New Mexico Petroleum Recovery Research
Center and accessible via the GOTECH web site at
http://octane.nmt.edu/
•
Geographic data from U.S. Department of Interior’s PLSS system
and the Carson National Forest including land grid, detailed roads,
surface feature boundaries, U. S. Geological Survey DRG
topographic maps, and surface waters. Other data from RGIS, the
New Mexico Resource Geographic Information System.
The product of this compilation effort, as delivered to the Carson National Forest,
is archived on an accompanying CD-ROM.
x
7
Chapter 3 Background Geology
3.1 Geologic setting
There are numerous references that describe the geology of the region
encompassing the Valle Vidal Unit, many of which are listed in Appendix 2 of this
report. The most recent published paper on the resource potential of the region
is by Hoffman and Brister (2003). Some of the discussions that follow are
repeated, paraphrased, or expanded from that paper.
The eastern Valle Vidal Unit is located in the southern part of the Raton
Basin, a Laramide geologic basin extending through southern Colorado and
northern New Mexico (Fig. 3.1). From a physiographic perspective, this area is
known as the Raton Mesa region, a highly stream-dissected, east-tilted mesa
that marks the transition from the Sangre de Cristo Mountains of the Southern
Rocky Mountains Province on the west, to the Great Plains Province on the east.
The eastern edge of Raton Mesa in New Mexico is a prominent escarpment west
of State Highway 64 between the towns of Raton and Cimarron. The western
edge of the Raton Basin/Raton Mesa is essentially marked by two prominent
hogbacks, locally known at the “The Wall” (westernmost) and “The Little
Wall”/“Ash Mountain” (easternmost) where rock units that crop out in the eastern
escarpment are tilted up against the Sangre de Cristo Mountains. From a coal
mining perspective, the area is often referred to as the Raton Mesa coal area or
region.
The eastern Valle Vidal Unit lies on the western edge of the Raton
Basin/Raton Mesa region. The bedrock geologic unit at the surface in the Unit is
the Poison Canyon Formation (Paleocene) that consists primarily of arkosic
sandstone and conglomerate. The present topography of the Valle Vidal Unit
(Fig. 1.1) is due to incision of modern stream valleys tributary to the Ponil and
Vermejo Rivers into a planation surface (Pleistocene or older) that caps the hills
and higher plateaus. Whitman Vega, the Beatty Lakes and other flat-floored
valleys appear to have supported natural lakes during past wetter climates, but
have for the most part since been captured and are drained by modern streams.
The western margin of the eastern Valle Vidal Unit as addressed in this study is a
north-northeast trending topographic ridge known as “The Rock Wall”, caused by
differential erosion around a swarm of three erosion-resistant igneous dikes (Fig.
3.2). A similar prominent northeast-trending dike (“Firewall Dike”) forms another
ridge informally named the “Firewall” (Fig. 3.3) that bisects the study area.
8
Figure 3.1 Geology and structural features of the Raton Basin, Colorado and New Mexico. Included are the eastern Valle Vidal Unit and coalbed
methane-producing areas in New Mexico. VP = Vermejo Park. Geology derived from New Mexico Bureau of Geology and Mineral Resources
(2003) and Tweto (1979). Figure modified from Hoffman and Brister (2003).
9
Little Costilla
Peak
Ash Mountain
The Rock Wall
Figure 3.2 (top) Photograph taken from the vantage point of the Firewall dike near where it
crosses North Ponil Creek looking westward. Three mountain ridges are visible in the photo
including The Rock Wall, Ash Mountain, and Little Costilla Peak. Photo by Christopher Haley.
10
Firewall Dike
Figure 3.3 (bottom) Photograph taken from same vantage point of Figure 3.2 looking southwest
along the Firewall dike. Note burned forest on the left and unburned trees on the right of the dike.
Photo by Christopher Haley.
11
3.2 Structural geology
Baltz (1965) provided a thorough description of the Raton structural basin,
paraphrased here. The Raton Basin is an elongate, slightly arc-shaped,
northerly trending, asymmetric structural downwarp formed during the Laramide
orogeny (Late Cretaceous to Eocene; Fig. 3.1). On its steeply dipping to
overturned western flank lies the Sangre de Cristo uplift. Structural relief on
Precambrian basement at the steep, western limb of the basin may be as much
as 12,000-15,000 ft (Cather, 2004). To the north are the Wet Mountains uplift and
Apishapa arch. The eastern flank dips gently (less than 3o) westward from of the
Sierra Grande arch. In New Mexico the post-Laramide Cimarron arch separates
the basin into two subbasins, the southern of which was named the Las Vegas
Basin by Darton (1928). The Upper Cretaceous to Paleocene coal-bearing
Vermejo and Raton Formations of the Raton Basin exist only north of the
Cimarron arch. Timing of basin formation is indicated by syndepositional
structures in the Vermejo and Raton Formations (Lorenz et al., 2003) and an
unconformity that places conglomeratic Paleocene Poison Canyon Formation in
angular contact with older rocks at the basin’s western and northern flanks (Baltz,
1965).
Cather (2004) describes multiphase Laramide development of the Raton
Basin based on the stratigraphic record preserved there. The first phase is
represented by the upper Pierre Shale (marine), Trinidad Sandstone (marginal
marine-shoreface), and Vermejo Formation (non-marine) that document the
regression of the Western Interior Seaway and progradation of sediments
derived from the incipient Laramide Brazos-San Luis uplift, the eastern part of
which is preserved as the Sangre de Cristo Mountains (Brister and Gries, 1994).
The Raton and Poison Canyon Formations are, in part, lateral equivalents
derived from the San Luis uplift and mark the medial phase of uplift and
associated basin subsidence. The third phase is represented in Colorado by
post-Poison Canyon formations. Subsidence of that phase may have been
limited to the northern parts of the basin.
Figure 3.4 is a combined geologic and structure contour map of the top of the
Trinidad Sandstone interpreted from a variety of data sources including oil and
gas wells and published measured sections on the southern edge of the basin.
The basin axis wraps around the eastern and southern flanks of the Vermejo
Park (VP on maps) dome. It is important to emphasize that there are limited data
points on which to base contour lines through the eastern Valle Vidal Unit. We
anticipate that the estimated contour lines will move as additional well control
points become available. The structure of the basin is an important factor in
determining the oil and gas potential of the eastern Valle Vidal Unit. The
influence of structure on each play type is discussed in Chapter 4.
It is notable that there is a general lack of faults shown on Raton Basin geologic
maps. This may be due in part to the heavy vegetative cover of the region that
12
obscures fault relationships. Numerous syndepositional faults are known to exist
and have been documented in road cuts (e.g. Lorenz et al., 2003). The
existence of fracture systems and their effects on reservoirs are well known (e.g.
Stevens et al., 1992). There appear to be two sets of extensional fractures that
have the potential to enhance permeability of reservoirs, with westerly and northnortheasterly azimuths (Scott Cooper, Sandia National Laboratories, 2003, pers.
comm.).
13
Figure 3.4 Structure-contour map of the top of the Trinidad Sandstone interpreted from well and surface data. VP = Vermejo Park. Contour
interval = 500 ft. Modified from Hoffman and Brister (2003).
14
3.3 Stratigraphic summary
Figure 3.5 is a summary stratigraphic column for the eastern Valle Vidal Unit
based upon Dolly and Meissner (1977) and Baltz and Myers (1999). It
demonstrates the stratigraphic formations present, their general lithologies, oil
and gas shows in the region, potential source rocks, and interpreted oil and gas
plays. Figure 3.6 is a type lithology log and Figure 3.7 is a cross-section for the
Unit.
Precambrian basement: Proterozoic supracrustal rocks in northern New
Mexico include metavolcanic, metasedimentary and plutonic rocks ranging from
1765 to 1650 Ma, and granitic rocks ranging from 1500-1400 Ma (Williams,
1990). In the vicinity of the Valle Vidal Unit, Grambling and Dallmeyer (1990)
describe the Proterozoic rocks outcropping in the Cimarron Mountains to the
south, and Smith (1988) and Grambling et al. (1989) describe these rocks in the
Taos Range to the west. Such rocks have no potential for generating oil and gas
and very low potential for being fractured reservoirs of oil and gas. The
Precambrian basement is capped by unconformities and may be overlain by
Pennsylvanian or Permian rocks beneath the Valle Vidal Unit.
Pennsylvanian strata: Pennsylvanian shale and siltstone sediments may
overlie Precambrian basement beneath the eastern Valle Vidal Unit. This
assumption is based on early work by Shaw (1956) and later workers that
suggest Pre-Pennsylvanian Paleozoic formations were likely eroded from the
region prior to deposition of the Sandia Formation (Morrowan-Atokan) as a
consequence of Mississippian initiation of uplift (De Voto, 1980) of the Ancestral
Rockies.
The Sierra Grande-Apishapa uplift, an element of the Ancestral Rocky
Mountains, was an emerging highland during the Pennsylvanian and early
Permian (Fig 3.8). Detritus was shed westward into the subsiding intermontane
Central Colorado trough, a basin bounded on the west by a southeastern
extension of the Uncompaghre uplift (Mallory, 1972a; De Voto, 1980). It is
possible, but unknown whether the Central Colorado trough was connected
southwestward to the Taos trough and Rowe-Mora basin exposed today in the
southern Sangre de Cristo Mountains.
x
15
Figure 3.5 Generalized stratigraphic column for the New Mexico portion of the Raton Basin.
Modified from Dolly and Meissner (1977).
16
Figure 3.6 Composite stratigraphic section,
vicinity of eastern Valle Vidal Unit, Raton
Basin, Colfax County, New Mexico.
Surface to Triassic: Gourley No. 1 Vermejo
Park, sec. 27, T31N, R17E. Triassic to
Precambrian: Continental No. 2 St. Louis,
Rocky Mountain, and Pacific, sec. 26,
T31N, R21E. From Grant and Foster
(1989). See original text for description of
units
17
Figure 3.7 West-east cross section, Raton Basin, New Mexico. From Grant and Foster (1989).
Wells:
1) Gourley 1 Vermejo Park, Sec. 27, T. 31N., R. 17 E.
2) Gourley 2 Vermejo Park, Sec. 16, T. 30N, R. 19 E.
3) Odessa 2 W. S. Ranch, Sec. 30, T. 30 N., R. 20 E.
4) Conoco 3 St. Louis, Sec. 18, T. 30 N., R. 22 E.
5) Conoco 1 St. Louis, Sec. 24, T. 30 N., R. 22 E.
6) Condron 1 Moore, Sec. 10, T. 29N., R. 24 E.
7) HNG 1 Roach, Sec. 1, T. 29 N., R. 25 E.
18
Figure 3.8 Principal late Paleozoic tectonic features of southern Colorado, northern New Mexico, and adjacent parts of Texas and
Oklahoma. From Baltz and Myers (1999).
19
In their memoir on the Paleozoic rocks of the region, Baltz and Myers (1999)
described the Sandia Formation as interbedded gray shale, carbonaceous shale,
fine- to coarse-grained sandstone and conglomerate, and thin limestone. Minor
coal seams were also noted. Gray and carbonaceous shales, and coal, are
possible source rock lithologies, whereas sandstones could be reservoir
lithologies. Grant and Foster (1989) allow for some potential for stratigraphic and
structural traps in the Pennsylvanian in the western Raton Basin. Foster (1966)
describes rocks similar to the Sandia Formation in the Conoco #2 Rocky
Mountain well (listed in Oil and Gas Well Database on accompanying CD-ROM)
drilled northeast of the Valle Vidal Unit by Conoco. No shows were reported for
those rocks in that well.
Permian strata: Subsidence of the Central Colorado trough continued into
the Permian as evidenced by the continued deposition of the conglomeratic
upper Sangre de Cristo Formation (Wolfcampian) which eventually lapped
eastward onto the Sierra Grande uplift. As the Ancestral Rocky Mountain
orogenic event drew to a close, the subdued topography was onlapped by the
Yeso Formation in some places, then capped by the marine Glorieta Sandstone
(Leonardian). The Glorieta Sandstone is a medium grained, well-sorted
sandstone. It is one of the deep saline aquifers used as a disposal zone for
produced waters from coalbed methane operations on the Vermejo Park Ranch
near the Valle Vidal Unit (Roy Johnson, NMOCD, 2004, pers. comm.). The
Glorieta Sandstone is a potential reservoir at the top of the PennsylvanianPermian clastic pile. However, no shows of oil and gas have been reported.
Triassic and Jurassic strata: According to Grant and Foster (1989), The
Triassic Dockum Group redbeds overlies the Permian strata with an
unconformable contact. The eolian Entrada Sandstone, otherwise known locally
as the Exeter Sandstone, in turn unconformably overlies the Triassic. The
Morrison Formation redbeds cap the Entrada Sandstone, also with an
unconformable contact. These formations lack source rock potential and have
generally not yielded shows of oil or gas. At the Vermejo Park Ranch, the
Entrada Sandstone is used as a disposal zone for produced water (Roy Johnson,
NMOCD, 2003, pers. comm.). The upper Morrison Formation yielded a gas
show of unknown quality while drilling a produced water disposal well on the
Vermejo Park Ranch (Roy Johnson, NMOCD, 2004, pers. comm.), but the show
apparently has not been confirmed by commercial production.
Dakota Sandstone through Pierre Shale (Cretaceous): The Lower to
Middle Cretaceous Dakota Group (a.k.a. Dakota Sandstone) was deposited upon
an unconformable surface. Its lower half is the deltaic Mesa Rica Formation
(Albian; Lucas et al., 1998) or Purgatoire Formation (Baltz, 1965), whereas the
upper half is the Romeroville Sandstone (Cenomanian; Lucas et al., 1998), a
shallow marine/shoreface unit. The basal unit represents an unconformitybounded transgressive event whereas the upper part is the base of a betterrepresented transgressive event in the region that includes the marine Graneros
20
Shale and is capped by the Greenhorn Limestone. These transgressions mark
the advance of the Cretaceous Interior Seaway that eventually covered northern
New Mexico. Baltz (1965) described the Dakota Sandstone as nearly all
sandstone with lenses of conglomerate in outcrops on the western margin of the
Raton Basin. The upper part of the Dakota grades into the marine rocks of the
overlying Graneros Shale.
The Dakota Sandstone is about 250 ft thick in the vicinity of the eastern Valle
Vidal Unit where it is comprised of porous sandstone interbedded with shale.
Where traps exist, the Dakota might make an attractive reservoir target with the
overlying Graneros Shale acting as source rock. The Dakota Sandstone has
yielded numerous shows of oil and gas in Colfax County (Foster, 1966), but no
commercial production. It is a produced water disposal zone at the Vermejo Park
Ranch (Roy Johnson, NMOCD, 2004, pers. comm.).
The Graneros Shale is dark gray and contains thin beds of bentonite,
limestone, and sandstone, whereas the Greenhorn is thin beds of limestone and
interbedded calcareous to chalky shale (Baltz, 1965). Overlying the Greenhorn
Limestone is the dark gray Carlile Shale, which is in turn overlain by the Niobrara
Formation. The Niobrara Formation is comprised of the Fort Hays Limestone
(lower part) and the chalky marls of the Smokey Hill Member. The mixed
calcareous and clay-rich composition of the Niobrara Formation makes it a
potential fractured reservoir as well as a potential source rock.
Above the Niobrara Formation is the 2000+ ft thick Pierre Shale. Most of the
Pierre Shale is dark gray noncalcareous shale. The upper several hundred feet
consist of gray, thin-bedded, fine grained sandstone intercalated with thin beds of
dark gray silty and sandy shale, essentially distal intertongues with the overlying
Trinidad Sandstone (Johnson et al., 1966). The Pierre is an oil- and gas-prone
source rock and has yielded numerous shows in the Raton Basin. Figure 3.9 is
a type electrical log that demonstrates the great thickness of the Pierre Shale
relative to other Mesozoic Formations in the Raton Basin.
Trinidad Sandstone through Poison Canyon Formation (CretaceousPaleocene): This section is the most important relative to coalbed methane
potential of the eastern Valle Vidal Unit. It contains coal beds that serve as
source rocks. Reservoir rocks include coal and sandstone beds. The coalbearing formations in the Raton Basin (Fig. 3.10) are underlain by the Trinidad
Sandstone. As thick as 130 ft, it forms a prominent cliff along the eastern edge
of the basin. Hills (1899) described the Trinidad Sandstone in the Raton Basin,
later to be defined by Lee (1917). The base of the Trinidad can be difficult to pick
in electric logs as there is a gradational contact between it and the underlying
Pierre Shale. The upward-coarsening sandstones show bioturbation and
commonly contain Ophiomorpha casts (Flores, 1987) suggesting a shallow
marine to shoreface depositional environment. The lower part of the formation
21
Figure 3.9 Type electric log for the eastern Valle Vidal Unit from the Gourley #1 Vermejo Park
well. The location of this well is problematic and is discussed in Section 4.1 of Chapter 4.
Figure from Grant and Foster (1989).
Figure 3.10 Generalized stratigraphic column for Cretaceous and Paleocene rocks in the Raton
Basin. From Flores and Bader (1999), modified from Pillmore (1969), Pillmore and Flores (1987)
and Flores (1987).
has ripple lamination that grades upward into planar and trough cross-lamination
(Flores, 1987), demonstrating an upward increase in depositional energy and
reflecting the overall shallowing and regression of the seaway.
Conformably overlying the Trinidad Sandstone is the coal-bearing Vermejo
Formation. However, Lee (1917) and Wanek (1963) recognized transgressive
tongues of the Trinidad Sandstone extending into the Vermejo Formation along
the southern margin of the basin. Both noted the general thinning of the Vermejo
Formation to the east. Lee (1917, p. 51) defined the Vermejo Formation for
exposures at Vermejo Park, and described it as the “coal measures lying
immediately above the Trinidad Sandstone.” This sequence of sandstone,
siltstone, mudstone, shale, carbonaceous shale, and coal averages
approximately 350 ft thick. The Vermejo Formation represents delta-plain
deposits landward of the shoreface delta-front and barrier-bar sediments of the
Trinidad Sandstone (Flores, 1987; Pillmore and Flores, 1987). The thicker coals
are commonly concentrated near the base of the Vermejo Formation in proximity
to the Trinidad upper shoreface sandstone.
In general, the Raton Formation overlies the Vermejo Formation with an
unconformable contact. Lee (1917) divided the Raton Formation into the
informal basal conglomerate, lower coal zone, a sandstone-dominated barren
23
series (middle barren sequence herein), and an upper coal zone. The Raton
Formation basal conglomerate is a 10- to 30-ft-thick pebble conglomerate to
granule quartzose sandstone eroded into the Vermejo Formation. Overlying the
basal conglomerate, the 100- to 300-ft-thick lower coal zone consists of
sandstone, siltstone, mudstone, carbonaceous shale, and thin, discontinuous
coal. This sequence represents meandering stream floodplain deposits that
grade upward into braided stream deposits of the overlying middle barren
sequence (Flores and Pillmore, 1987; Johnson and Finn, 2001), which varies
from 165 to 600 ft thick. The middle barren sequence merges with the Poison
Canyon Formation to the west (Pillmore and Flores, 1987). The upper coal zone
is a return to finer-grained deposits in an alluvial plain environment (Flores,
1987). Peat swamps developed between the meandering stream channels. Coal
beds are lenticular within the upper coal zone but tend to have greater thickness
than those in the lower coal zone of the Raton Formation.
The Raton Formation is overlain by and intertongues to the west with the
Poison Canyon Formation; the contact can be gradational in parts of the basin.
Where the contact intersects the surface, it is mapped as a transitional area (e.g.
as mapped by the New Mexico Bureau of Geology and Mineral Resources and
others). This is due in part to extensive vegetative cover, but also due to the lack
of a detailed study of the Poison Canyon Formation. The Poison Canyon
Formation consists of coarse grained to conglomeratic arkosic sandstones. This
unit represents prograding conglomeratic lithofacies derived from the Sangre de
Cristo uplift. As mentioned previously, this formation is the primary bedrock at
the surface in the eastern Valle Vidal Unit.
Oligocene and younger igneous rocks: All of the stratigraphic units
described above are intruded or domed by Oligocene or younger igneous
intrusions somewhere within the region. These intrusions include dikes, sills and
laccoliths. Miggins (2002) conducted an extensive study dating many of the
igneous features of the region, reporting ages from 33 to 19.7 Ma. At least three
oil and gas exploratory wells penetrated igneous rocks (rhyodacite) at shallow
depths (less than 4000 ft) over the Vermejo Park dome. Other igneous intrusions
in the region include sills in coal beds and dikes that penetrate the entire
stratigraphic section. Rock samples from the Firewall dike in the eastern Valle
Vidal Unit yielded an Oligocene age of 28.0+0.8 Ma (Million years before
present) using the 40Ar/39Ar dating method (Geochronology Laboratory at the
New Mexico Bureau of Geology and Mineral Resources, March 18, 2004, unpubl.
report).
x
24
Chapter 4 Estimation of Resource Potential and Development
4.1 Oil and gas exploration history
Resource potential encourages operators to drill exploratory wells. As
exploration proceeds shows of oil and gas and other encouraging information
help to build a picture of probable resources available, sometimes leading to
commercial production. More than 150 exploratory wells have been drilled in
Colfax County, 74 of which reached the Cretaceous Dakota Sandstone.
Beginning in 1924 most early exploration focused on finding oil because it could
be trucked or shipped by rail to refineries. On the other hand, natural gas
required pipelines for transportation. Several larger companies made brief
exploration forays into the basin, notably Continental Oil with nine wells in 1954–
1955, Pan American with nine wells in 1957–1960 and later as Amoco with eight
wells in 1968–1974, and Odessa Natural Gas with eight wells in 1972–1973.
These early attempts commonly reported gas shows in the Raton and Vermejo
Formations and oil and gas shows in the underlying Trinidad Sandstone through
Dakota Sandstone (Baltz, 1965; Foster, 1966; Woodward, 1984). The overall
results suggested that the basin might be analogous with the Denver–Julesburg
(Woodward, 1984) or San Juan Basins in terms of widespread oil and gas in
fractured, low permeability formations. However, the Raton Basin lacked the
pipeline infrastructure and moderately porous sandstone reservoirs that made
the San Juan Basin so prolific beginning in the late 1950s.
Pennzoil began exploring the potential of its Raton Basin minerals estate in
1981 with several noncommercial deeper Cretaceous tests and shallow coal
tests. By 1989 it had assembled a huge 780,000-acre mineral estate, purchased
in part from Kaiser Steel in 1989 (Whitehead, 1991). The successful coalbed
methane development boom in the San Juan Basin, coupled with Section 29 tax
credits for development of unconventional gas reservoirs, encouraged Pennzoil
to evaluate the coalbed methane potential around the Vermejo Park area with
approximately 30 wells in 1989–1991, 22 of which were produced briefly to
evaluate economic viability (Whitehead, 1991). Pennzoil had apparently used the
older Kaiser data set as they focused their coal bed exploratory program on
areas where the coal was thick and of higher thermal maturity. Unfortunately, the
Pennzoil program suffered from the lack of a pipeline, low gas prices at that time,
and expiration of the Section 29 tax credits. Information derived from the
Pennzoil data set was studied and published in various reports by the Gas
Research Institute, notably those of Stevens et al. (1992) and Tyler et al. (1995).
By 1994 the first pipeline was built to transport Raton Basin coalbed methane
from the Colorado part of the basin, and a development boom began,
accelerating as gas prices improved through the late 1990s. A group of several
companies, now consolidated to El Paso Raton LLC, acquired the Pennzoil
Vermejo Park mineral estate in New Mexico and began to define the reserves in
1999 with exploratory stratigraphic test wells, many of which were cored.
25
Commercial coalbed methane production in the New Mexico part of the Raton
Basin began in October 1999 upon completion of a pipeline. Subsequent
development has expanded concentrically within the areas identified as potential
by Pennzoil’s 1989–1991 exploratory efforts.
It is important to note that there have been no significant oil and gas
exploratory wells drilled within the boundaries of the eastern Valle Vidal Unit to
test the three plays listed below. Several shallow coal investigation drill holes
were drilled by Kaiser and Pennzoil in the eastern Valle Vidal Unit that support
the existence of a coalbed methane play. One oil and gas test was reported, the
Gourley #1 Vermejo Park, the location of which would be within the Valle Vidal
Unit according to a survey plat filed prior to drilling of the well. This well has
been used as a critical data point in the literature (Foster, 1966; Grant and
Foster, 1989). Considerable time, effort, and expense were expended in the fall
of 2003 to locate the Gourley well on the ground and investigate conflicting
information in paperwork on file at the New Mexico Bureau of Geology and
Mineral Resources. We believe that the Gourley well was drilled at a location
approximately four and one half miles north of the Valle Vidal Unit on the
Vermejo Park Ranch as indicated by a location description on the electric log for
the well and consistent with the elevation reported for the well (see Oil and Gas
Well Database on accompanying CD-ROM for well information). This location is
supported by a map provided by the New Mexico Oil Conservation Division
(Osterhoudt, 1990, unpublished) that shows the location of the Gourley well in
the vicinity of wells drilled or planned by Pennzoil in their 1989-1992 coalbed
methane evaluation program.
The lack of oil and gas tests within the Valle Vidal Unit does not compromise
the analysis here as the plays described below are not limited in area to the Unit
and there is abundant well data in Colfax County upon which to base these
plays. The plays and the ranks assigned to them are based on study of data
from throughout the southern Raton Basin.
4.2 Ranking potential for occurrence
One goal of the RFDS is to estimate the resource potential of the eastern Valle
Vidal Unit. Following a review of the literature and past exploration and
production activity, we describe the potential of three plays, each play having its
own geologically similar traps, potential targets for accumulation of oil and/or gas
in porous reservoirs. A modern approach to evaluating oil and gas potential is to
examine the factors that contribute to a petroleum system. According to Magoon
and Dow (1984), “Petroleum system studies describe the genetic relationship
between a pod of active source rock and the resulting oil and gas
accumulations.” The petroleum system analysis qualifies/quantifies the presence
of source rocks, capacity and timing of source rocks to produce oil and/or gas,
migration of oil and gas to traps, and the location and types of accumulation of oil
26
and gas in reservoir rocks where traps exist. Traps in turn are sealed in some
capacity. Often, only parts of the petroleum system are apparent or obvious,
other parts must be inferred. See Broadhead (2002) for a layman’s description of
the origin of oil and gas and the physical requirements for accumulation.
Demonstrated presence of oil or gas by way of “shows”, or even better,
production from wells, is the best clue of oil and gas potential. Shows indicate
that oil/gas have been generated to some extent and are present. However,
presence or lack of shows does not determine presence or absence of economic
accumulations. Economic potential of a resource can be estimated, but in the
final analysis is determined by producing oil and gas economically to the
marketplace.
A petroleum system-type analysis helps to qualify the oil and gas potential by
ranking the presence or absence of key factors. For the purposes of this RFDS,
the following ranking system, consistent with petroleum system concepts, was
accepted by the Carson National Forest for ranking potential for occurrence
by play:
High: the demonstrated existence of source rock, thermal maturation,
reservoir strata possessing permeability and/or porosity, and traps.
Demonstrated existence is defined by physical evidence or documentation
in the literature.
Medium: geophysical or geological data indications that the following
may be present: source rock, thermal maturation, reservoir strata possessing
permeability and/or porosity, and traps.
Low: specific indications that one or more of the following may not be
present: source rock, thermal maturation, reservoir strata possessing
permeability and/or porosity, and traps.
None/very low: demonstrated absence of a petroleum system. This rank
would apply to rocks that do not fall into one of the following plays and is
therefore not used in this study.
4.3 Ranking potential for development
Another goal of this RFDS is to estimate potential for development of the
potential oil and gas resources. For the purposes of this discussion, the
potential for development is estimated after a ranking assignment for potential of
occurrence of the resource. The geologic conditions for oil and gas reservoirs
below the eastern Valle Vidal Unit suggest that the resources there will most
likely yield unconventional-type, fractured, low-permeability and coalbed methane
reservoirs. Such reservoirs vary significantly from conventional porous and
27
permeable reservoirs that have historically better recovery volumes and rates of
production, and economics. Unconventional reservoirs tend to be economically
marginal and be technically challenging to drill and/or complete. However, the
key is that they are often economically marginal, not subeconomic. The
economy of scale plays an important role in development of these reservoirs.
Economically marginal and technically challenging conditions do not deter
operators from drilling and/or completing wells that will produce. By fine-tuning
their economics and techniques to produce such reservoirs, operators can add
significant cumulative resources to their long-term reserves inventory. As fuel
prices are expected to rise (as domestic production struggles to supply
increasing demand) long-lived reservoirs will increase significantly in value.
Conventional reservoirs are often discrete accumulations of oil and gas,
whereas unconventional reservoirs are often blanket-type accumulations where
oil and gas are trapped by the low capacity of the rocks to conduct fluid under
reservoir physical conditions. The unconventional nature of the potential
resources is discussed further in the next section. The following simple scheme
was used for ranking potential for development by play:
High: There is high potential for blanket-type unconventional resource
occurrence and it is economically and technically feasible to develop most
prospective locations using conventional technology within the time
constraints of the RFDS based on current or anticipated well spacing rules
that apply to the area being developed. For conventional resources, this
ranking assumes a high potential for resource occurrence, and favorable
technical and economic conditions for development of conventional oil and
gas fields. Geophysical data may be desirable to guide development of
conventional and unconventional plays.
Medium: The potential for occurrence is ranked high or medium, but viable
production from the play has not been demonstrated on or near the area
being evaluated. This ranking assumes that there will be sufficient interest
to drill one or more wildcat wells to test resource occurrence, and evaluate
economic and technical feasibility. Speculative geophysical data acquisition
may be attempted to further evaluate the play.
Low: The potential for occurrence is ranked low or very low. It is unlikely that
wildcat wells will be drilled in the 20-year time frame to specifically test the
play because of either low prospectivity or poor economic potential.
Speculative geophysical data acquisition may be attempted to further
evaluate and possibly upgrade the resource potential rank.
28
4.4 Vermejo-Raton coalbed methane play
(Potential for occurrence = High, Potential for development = High)
Coalbed methane has been recognized as an important and widespread
resource in the U.S. only since the 1980s. There are a few key papers that
describe the conditions favorable for coalbed methane reserves in the Raton
Basin. A pioneering study of coalbed methane potential in the Raton Basin by
Jurich and Adams (1984) estimated a total resource of 8–18 trillion cubic feet of
gas (Tcf) for the entire basin. Close (1988) updated the earlier work and included
a detailed study of the depositional environments, cleat orientation and fracture
patterns, thermal maturity parameters, and regional thermal history of the basin.
Close and Dutcher (1991) estimated the coalbed methane resource to be 40
billion cubic feet (Bcf) per square mile with an estimated ultimate reserve base of
one Tcf. The Gas Research Institute (GRI) published a coalbed methane
assessment of the Raton Basin (Stevens et al., 1992) that summarized reservoir
characteristics and estimated the mean coalbed methane resource of the Raton
and Vermejo coals at 10.2 Tcf. New data from wells drilled in the basin were
incorporated into the GRI report along with gas desorption measurements and
new vitrinite reflectance data, collected in part from coal cores available at the
NMBGMR (Stevens et al., 1992, p. 41). Flores and Bader (1999) summarized
previous studies and future potential of mining and coalbed methane without
including a specific resource assessment of the basin. Johnson and Finn (2001)
evaluated the potential for basin-centered gas in the Raton Basin in the
sandstones in the Trinidad, Vermejo, and Raton Formations.
An exploration and pilot development drilling project conducted by Pennzoil in
1989–1991 demonstrated that a coalbed methane resource existed in the New
Mexico portion of the Raton Basin, but economics and lack of a pipeline
prevented the onset of production until 1999. In 1999 a new pipeline allowed
production of coalbed methane to begin on the Vermejo Park Ranch which lies
adjacent to, and north of, the Valle Vidal Unit. All current coalbed methane
production operations in the New Mexico portion of the Raton Basin are being
conducted by El Paso Raton LLC in cooperation with the Vermejo Park Ranch.
Hoffman and Brister (2003) reviewed the status of the play as of May 2003 when
256 wells had accumulated more than 22 billion cubic feet of coalbed methane
from coals in the Upper Cretaceous to Paleocene Vermejo and Raton
Formations. An additional 44 wells were producing as of the end of December
2003. The production is from two areas; one is northeast of Vermejo Park and
the other generally southwest of Vermejo Park and adjacent to the Valle Vidal
Unit. In addition, potential for production from Raton Formation sandstone
reservoirs is indicated for a large area where coal beds are currently being
developed. The Vermejo Park Ranch is anticipating significant additional
development by El Paso Raton LLC in the region between the two existing areas
of production and between the southwestern producing area (VPR D and B) and
the eastern Valle Vidal Unit (Rich Larson, Vermejo Park Ranch, 2003, pers.
comm.).
29
Coalbed methane is similar to natural gas produced from conventional gas
fields, varying only slightly in molecular composition. Coalbed methane is
considered an unconventional resource. The coal assumes the function of
source rocks, having high total organic carbon, and of reservoir rocks, having the
potential for storing methane. The matrix of coal generally has low values of
porosity, but it stores methane nonetheless due to physical adsorption of
methane molecules on organic matter particles. Coals have cleats (fractures)
that create a drainage network for moving water and methane through the coal
bed; the two products are extracted together with water being an unavoidable
byproduct. Chapter 8.4 includes discussions of the challenges faced when
dealing with produced water.
Coal thickness, bed continuity, and coal quality are important factors to
consider in evaluating coalbed methane resource potential. Most of the coalbed
methane wells in the New Mexico part of the Raton Basin produce methane from
the Vermejo Formation with contributions in some wells from the Raton
Formation. Well logs were examined from throughout the Vermejo Park
producing area at a density of one well per square mile where available,
recording thickness of coal beds greater than or equal to 1 ft thick. Lack of lateral
continuity for most of the coals in the Vermejo and Raton Formations dictates
grouping the coals together by formation to do any valuation of the overall
thickness characteristics. Table 1 is a compilation of the publicly available data.
These wells are concentrated in the areas northeast and southwest of Vermejo
Park. The data are derived almost entirely from interpretation of geophysical logs
from producing wells. The entire Raton Formation was not recognized in the
open-hole geophysical logs because wells are cased to 300-ft depth to protect
shallow ground water. Any coals above this depth are not represented in the data
in Table 1. The average and maximum total coal thickness and number of
seams is greater in the Raton Formation. The maximum average seam thickness
is the only statistic that is significantly greater for the Vermejo Formation. A tally
of individual seams from 1 ft to > 10 ft from these same data indicates 84% of
Raton coals are 1–3 ft thick, whereas 93% of Vermejo coals are in this same
thickness range. Vermejo coals 5 ft thick or greater make up about 8% of the
data set, and Raton coals 5 ft thick or greater account for 3% of the data set.
30
Table 4.1. Coal thickness and seam properties of Vermejo and Raton formations. Data from
coalbed methane and oil and gas geophysical logs. Raton coal picks from logs with 1400 ft of
section from base of Raton. Vermejo coal picks from logs with base of Raton and top of Trinidad.
(updated 5/19/04)
Total Coal (ft)
Formation Raton
26
Average
64
Max
8
Min
59
Count
12
Std
Deviation
No of Seams
Average seam
thickness per well
Vermejo Raton
Vermejo Raton
Vermejo
15.97
14
7
2
3.1
33
30
13
3.3
10.7
4
4
2
1.2
1.3
133
6.5
6
2
0.5
1.6
Vermejo Formation: The Vermejo Formation contains some of the thickest
coals in the Raton Basin. Figure 4.1 is a map of net Vermejo Formation coal
derived from well log interpretation (sum of Vermejo coal beds greater than or
equal to 1 ft thick, wells with complete section of Vermejo). In the wells
examined, net Vermejo coal ranges from 4 to 33 ft supporting observations from
surface work and mining that describe lenticularity of coal beds and associated
variability in individual and net total coal bed thickness. Figure 4.1 further
illustrates the lenticularity or lack of continuity of the coal seams within the
Vermejo Formation. Given the current density of wells we believe that there is
insufficient control to draw meaningful contour maps. Wells examined that are
encompassed by the two producing areas average approximately 18 ft net
thickness for the southwestern area (63 wells) and 16 ft net thickness for the
northeastern area (57 wells). Several wells on the map fall outside the producing
areas (thus 133 wells total).
Figures 4.2 and 4.3 are stratigraphic cross sections based on wells spaced
approximately 3/4 to 1 mi apart, and they depict coal beds interpreted from
geophysical logs and those coals that were completed for coalbed methane
production. Coal beds cannot be readily correlated between wells at this well
spacing. This degree of stratigraphic complexity adversely affects the ability to
efficiently drain reservoirs with widely spaced wells at the current density of 1/2
mi spaced wells (area of 160 acres/well). This does not suggest a lack of
potential, rather it reinforces the concept of necessity to drill more wells to more
efficiently drain the reservoir. Overall, the Vermejo Formation thins eastward, but
the number and thickness of coal beds does not appear to change significantly.
The Vermejo Formation may be important for coalbed methane production over a
large area.
31
Figure 4.1 Vermejo Formation net coal thickness interpreted from geophysical logs of wells with complete Vermejo section. VP = Vermejo Park.
31
Figure 4.2 Cross-section A-A’ (west to east). Approximate spacing between wells is 1 mi. Line of cross section shown on maps in Figs. 4.1 and 4.4. Wells
arranged such that the top of the Vermejo Formation is the stratigraphic datum. The top of the Trinidad Sandstone is the base of the well columns. The top of
each well column is the top of the open-hole logged part of the well from which data are derived. Depth markers (e.g. –500 ft) are indicated for each well.
“Perforation” refers to points where the well that have been targeted for production.
33
Figure 4.3 Cross-section B-B’ (west to east). Approximate spacing between wells is 3/4 mi. Line of cross section shown on maps in Figs. 4.1 and 4.4. See Fig.
4.2 for comments on cross section construction.
34
Raton Formation: The lower coal zone of the Raton Formation has several
thin lenticular coals that have been completed in many coalbed methane wells.
The upper coal zone may have more economic potential for coalbed methane as
it tends to have some lateral continuity. The York Canyon coal bed in the upper
coal zone averages 5–6 ft thick and was the principal bed mined at the York
Canyon complex that lies between the two Vermejo Park coalbed methane
producing areas. In the Upper York or Left Fork district where the Cimarron
underground mine operated, there are two coals that range in thickness from 3.5
to 11 ft.
Figure 4.4 is a map of net Raton Formation coal from well log interpretation
(sum of Raton coal beds greater than or equal to 1 ft thick, wells with a minimum
of 1,400 ft of Raton section logged). Like the Vermejo coal beds, Raton coals
tend to be discontinuous or lenticular. We believe that the existing well control
does not reveal their complexity, making contour mapping problematic. In the
wells examined, net Raton coal ranges from 8 to 64 ft thick. Wells examined that
are encompassed by the two producing areas average approximately 24 ft net
thickness for the southwestern area (29 wells) and 29 ft net thickness for the
northeastern area (30 wells). It is significant to point out that many wells do not
produce from the upper coal zone, particularly in the southwestern area. Most
wells are not completed above the 1,000-ft (305-m) depth presumably to avoid
excessive water production. Figures 4.2 and 4.3 show that, like the Vermejo
Formation, individual coal beds in the Raton Formation have limited extent and
thickness and tend to be concentrated into zones.
35
Figure 4.4 Raton Formation net coal thickness interpreted from geophysical logs. Wells included only where 1,400 ft or more of Raton Formation was
logged. VP = Vermejo Park.
36
Coal quality: The Vermejo and Raton Formations contain low-sulfur,
moderate-ash coals of high-volatile A to B bituminous rank. The quality of the
coals within the two formations does not vary significantly (Hoffman, 1996).
However, there are areas within the coal field where Oligocene and younger sills
have intruded coal seams, destroying the economic potential of the seam. The
high-volatile bituminous rank indicates that these coals have reached the
bituminization stage (Levine, 1993) when generation and entrapment of
hydrocarbons takes place, vitrinite reflectance (%Ro—a method to estimate
thermal maturity) increases to 0.6–1.0, and the moisture content of the coal
decreases. Less than half of the prospective area as delimited by the presence of
thermally mature coal has been developed.
Coal rank and maturity indicators in the Raton Basin coal beds strongly
suggest that the coalbed methane gas being produced today was thermally
rather than biologically generated. Thermal generation depends in part on depth
of burial and regional heat flow. There is evidence from fission track studies
(Hemmerich, 2001) that approximately 3600 ft of denudation has occurred in the
Vermejo Park region since the Miocene. Miggins (2002) conducted an extensive
study dating the igneous intrusions of the region, and he reported ages from 33
to 19.7 Ma, most being clustered around 25 Ma. Like the Spanish Peaks in
Colorado, the structural dome of Vermejo Park is probably a result of laccolithic
intrusion; wells on the Vermejo Park structure bottom in igneous rocks at
atypically shallow depths relative to wells outside of the dome. Although dikes
and sills in the area tend to have a limited direct effect (contact metamorphism)
on adjacent rocks, regionally elevated heat flow and convection of associated hot
ground water can influence a much greater volume of the coal-bearing
sequences. Thus the combination of both maximum paleoburial depth and
elevated heat flow during the Miocene is the likely cause for relatively high
thermal maturity of coals shallowly buried today.
Some unpublished vitrinite reflectance (%Ro) thermal maturity data are
available for the Raton Basin in addition to the published data (See Oil and Gas
Well Database on accompanying CD-ROM). Most of these data are from surface
channel samples, either from outcrops or at mine faces; the remainder are from
cores. There are 19 samples from the Raton Formation and 14 samples from the
Vermejo Formation. Figure 4.5 shows the deep and surface vitrinite reflectance
data and the producing areas within the Raton Basin in New Mexico. The data
shown have not been adjusted to any set depth or datum. The data close to the
edge of the basin range from 0.45 to 0.75 %Ro. Given that coal is primarily a
gas-prone source rock and that thermogenic gas becomes significant at
approximately 0.8 %Ro, these areas have possible potential for coalbed methane
but they are relatively thermally immature compared to the northwest corner of
the New Mexico portion of the Raton Basin which has the greatest coalbed
methane potential with %Ro greater than 0.8. We believe that coals above the
water table have no production potential but public domain water table data for
the coal-bearing units was not available for analysis in this study.
37
In Figure 4.5 an attempt was made to draw a smooth 0.8 % Ro contour through
the basin, guided in part by structural elevation of the Trinidad Sandstone, but
honoring control data, to delineate those areas that are most prospective. Note
that this line is dashed due to uncertainty. Unfortunately there is only one control
point in the Valle Vidal Unit, very near the northern boundary with the Vermejo
Park Ranch. Although the contour was drawn to honor this data point, the line
probably depicts a minimum scenario. It is truly unknown how the line should be
drawn through the eastern Valle Vidal Unit (including only part of the unit in the
prospective area), or around the eastern Valle Vidal Unit (including the entire Unit
in the prospective area). The igneous intrusions in the southern part of the study
area may have elevated thermal maturity of coals in the southern part of the
eastern Valle Vidal Unit and this could easily justify including the entire area.
Due to the uncertainties, the authors have chosen not to discount any part of the
eastern Valle Vidal Unit on the basis of thermal maturity because of a simple lack
of data in that area that could be proved by the drilling of one or more core tests.
Stevens et al. (1992) were willing to assign a 4-8 Bcf/mi gas in place estimate to
this area. It is our interpretation that in the entire eastern Valle Vidal Unit, the
coal is below the water table and minimally mature such that coalbed methane is
present and will be an inviting target for development by potential future mineral
lessees.
38
Figure 4.5 Map of vitrinite reflectance (%Ro), a source rock thermal maturity indicator. Area of probable coalbed methane productivity is suggested by
thermal maturity contour value >0.8 % Ro; area of possible potential for coalbed methane production is suggested by thermal maturity contour value
>0.6%Ro. Vitrinite reflectance data is from the Oil and Gas Well Database on the accompanying CD-ROM. Points depicted include only raw data that
have not been adjusted for depth and come from a variety of sources of unknown reliability. Coal mines depicted are further described in the Raton coal
mines database on the CD-ROM that accompanies this report. VP = Vermejo Park.
39
Related gas sands: In their 2001 study, Johnson and Finn consider the
Raton Formation through Trinidad Sandstone in the Raton Basin to have basincentered gas potential. The basal Raton Formation conglomeratic unit shows
evidence of gas saturation in many wells in both producing areas. The presence
of gas in sandstones is suggested from well logs where neutron log porosity is
reduced and density porosity is elevated such that there is a crossover of the two
log curves. Figure 4.6 is a well log cross section through the western part of the
northeastern coalbed methane production area. The cross section shows all
sand beds greater than 6 ft in thickness and coal beds greater than or equal to 1
ft thick, and indicates which sands have the well log gas effect. These wells are
spaced only 1/2 mi apart, but similar observations can be made about the
continuity of sandstone beds as for coal beds. Although the sandstone beds fall
within zones, it is often difficult to correlate individual lenticular fluvial sandstone
beds between wells. A number of wells in the southwestern producing area
show similar log cross-over and two wells have been completed as sandstoneonly wells. Chapter 5 includes a production analysis of the VPR D area, adjacent
to the Valle Vidal Unit that suggests gas sands do contribute to production from
coalbed methane wells.
Potential for occurrence: Coal beds exist in the Raton and Vermejo
Formation in the eastern Valle Vidal Unit at similar depths as in the adjacent
Vermejo Park Ranch where economic coalbed methane production operations
are ongoing. Coalbed methane production in the adjacent property is expanding
over time suggesting that economics have continued to be favorable. There is
no reason to believe that this will change as development approaches the
boundary of the Valle Vidal Unit. Although bed thickness of these coals is
minimal, multi-bed completions allow for enough coal per well to justify
development based on proven production from multiple such wells. The coals
are lenticular and difficult to correlate between wells at 160 acre per well spacing
suggesting that this may not be the optimum spacing (requires closer well
spacing) for development in the long term. The coals are high quality and
assumed to be minimally thermally mature although there is uncertainty in this
assumption and new well data is needed to prove and quantify this. As will be
discussed in Chapter 5 the thermally generated gas resides in the coals as
adsorbed and free gas. Distance of migration and migration pathways are not a
significant factor because the gas is essentially trapped where generated,
suggesting low formation permeability. Some interbedded sandstone units have
gas saturations that probably contribute to production, but these don’t appear to
be discreetly trapped. This is a regional play with a large area of prospectivity;
there is no need to rely upon presence of discreet traps for production. The
combination of these factors leads to the conclusion that the potential for
occurrence cannot be ranked less than high.
40
S6-T31N-R19E S5GL 8579
TD 2101
T31N-R19E
GL 8639
TD 2525
S5-T31N-R19E
GL8592
TD2735
West
S4-T31N-R19E
GL8518
T2785
East
Figure 4.6 Cross section that provides a closer spaced view of the western part of cross section A-A’ (Fig. 4.2).
Sandstone beds interpreted to be gas charged are indicated by red rectangles. Approximate spacing between
wells is ½ mi. See caption for Figure 4.2 for other comments on cross section construction.
41
Potential for development: Coalbed methane plays in general tend to be
widespread reservoirs that cover large areas. The physical characteristics of the
coal-bearing intervals determine how consistent production will be well-to-well.
In plays like the Raton Basin play, stratigraphic complexity could be responsible
for significant inconsistency in production as compared between wells. As such,
development operations tend to mimic modern manufacturing businesses where
every well is constructed similarly and the economy of scale becomes an
important factor in minimizing cost. Often there is significant per well deviation
from average well production, but better wells are not easy to predict, nor poor
wells avoidable, prior to the expenditures of well drilling and completion. Thus,
most locations will be drilled with the average production from all wells
determining the economics of the total operation. The potential for development
of coalbed methane over the entire eastern Valle Vidal Unit is predicted to be
high because the resource potential is high and infrastructure requirements and
development investments will encourage operators to maximize the number of
locations developed to improve the financial bottom line. In order for operators to
take advantage of the economy of scale, large contiguous areas of development
would need to be allowed for in the Forest Plan.
4.5 Pierre-Dakota oil and gas play
(Potential for occurrence = High, Potential for development = Medium)
Thousands of feet of shale formations with source rock potential combined
with peak gas-generating thermal maturity conditions make the Pierre Shale
through Dakota Sandstone interval an attractive play on a first-pass examination.
More than 74 Dakota wells have been drilled in Colfax County and many have
reported oil and gas shows. However, no commercial production has been
established to date. Lack of a pipeline before 1999 was a good explanation for
this and there have been no attempts to establish production in this stratigraphic
interval since the pipeline was constructed. There are two possibilities for
occurrence examined here, one being conventional traps and the other being a
blanket-type, fractured, low-permeability, unconventional play.
Shows and thermal maturity: Oil and gas shows in Cretaceous rocks have
been described by a number of authors, notably Baltz (1965), Foster (1966),
Woodward (1984; 1987), Grant and Foster (1989), and Johnson and Finn (2001).
In addition, oil and gas shows are commonly noted on scout cards (well records)
from Cretaceous-penetrating wells. Wells that found Cretaceous rocks at
shallow depths on the eastern basin margin or outside of the basin are typified by
oil shows, whereas those wells that have drilled Cretaceous rocks below the
thermally mature coals have had predominantly gas shows. Marine shales,
particularly those described as dark gray to black, tend to contain oil-prone
source rocks. When thermal maturity rises through time due to burial and
elevated formation temperature, organic matter reaches the “gas window” where
oil molecules begin to crack into lighter gaseous molecules. Thus oil-prone rocks
42
could yield primarily natural gas above about 1.0 % Ro vitrinite reflectance, the
thermal condition assumed for these rocks in the axial area of the basin.
Conventional traps and accumulations in reservoirs: There are two
issues to examine here. One is that in the Cretaceous strata there is a shortage
of conventional-type reservoir rocks with reasonable porosity and permeability,
an exception being the Dakota Sandstone. The other issue deals with traps. A
convenient horizon for mapping Cretaceous structure in the basin is the Fort
Hays Limestone. A structure contour map of the top of the Fort Hays Limestone
(Figure 4.7) based on a very small number of data points reveals no inter-basin
positive structures of large scale. However there is not enough well control to
demonstrate the Vermejo Park dome (VP on figures), a large dome caused by
intrusion of a laccolith, thus structures of considerable size could be present.
Small structures are more likely. A deliberate search, perhaps seismically driven,
for small structural and stratigraphic traps will be required to find areally limited
reservoirs of gas in the Dakota Sandstone in the eastern Valle Vidal Unit.
Unconventional reservoirs: Woodward (1984) summarized the potential for
fractured low permeability reservoirs in the Raton Basin. Carbonate-rich beds of
the Greenhorn Limestone and the overall Niobrara interval, and siliceous silty
and sandy interbeds of the Graneros, Carlile, and Pierre Shales may provide
naturally fractured reservoirs. Similar reservoirs include the Lewis Shale of the
San Juan Basin, an economically marginal (not subeconomic), gas producing
formation where fractured siliceous zones contribute on average less than ½ Bcf
of gas to Mesaverde Group wells. The Barnett Shale play of the Fort Worth
Basin in Texas is probably the most outstanding example of an economically
marginal play fractured shale play that became a wildly lucrative play due to
technical advances in artificial hydraulic fracture stimulations (Brister and
Lammons, 2000). However, Cretaceous shale formations tend to be sensitive to
damage by the fresh water used to perform these stimulations (Brister, 2001) and
more expensive to stimulate satisfactorily. Fractured “shale” plays are an
emerging contributor to U. S. gas resources, but there is much left to understand
about the physical conditions of the reservoirs and the technical requirements for
accessing the reserves economically.
43
Figure 4.7 Structure-contour map of the top of the Fort Hays Limestone interpreted from well data. VP = Vermejo Park.
44
Potential for occurrence: The potential for occurrence of a predominantly
gas fractured Cretaceous play in the eastern Valle Vidal Unit is high based upon
the demonstrated shows of oil and gas in the Raton Basin. If significant
reservoirs exist, gas would be trapped in discreet stratigraphic and structural
traps in the Dakota Sandstone or in blanket-type fractured “shale” reservoirs, the
latter being more likely to exist.
Potential for development: The potential for development is medium at
best within the 20-year time frame of the RFDS. There is no current activity
focusing on exploring in this play at this time. It is possible that geophysical
prospecting might be applied to search for fracture zones or conventional traps,
with seismic data being the most expensive but effective geophysical tool.
Importantly, this play would be tested several times as deep water disposal wells
would be drilled to accommodate produced water from a coalbed methane
development program. Encouraging shows might encourage drilling of additional
wells to confirm the shows, but these wells could be “twinned” with coalbed
methane production wells by drilling both wells from the same pad. Another
possibility is that exploratory wells could be planned such that if they fail to
establish production in the play, they can be plugged back and recompleted as
coalbed methane wells. This is an economically favorable practice if conducted
in early stages of development of the eastern Valle Vidal Unit.
4.6 Pennsylvanian-Permian gas play
(Potential for occurrence = Low, Potential for development = Low)
The premise of this play is that there is a westward-thickening wedge of
Sandia Formation (Pennsylvanian) rocks containing potential petroleum source
rock lithologies beneath the eastern Valle Vidal Unit. Given the level of maturity
of source rocks in the Cretaceous-Paleocene coal-bearing formations at
relatively shallow depths, source rocks in the Sandia Formation, if they exist,
would be mature. They could potentially be overmature where hydrocarbons
have been cooked to form carbon dioxide (CO2). Foster (1966) reported CO2 in
Permian rocks in the Conoco #3 Rocky Mountain well (listed in Oil and Gas Well
Database on accompanying CD-ROM). Other shows have been noted in the
Dakota and Permian rocks east of the Raton Basin. It should be noted that CO2
is also commonly found associated with volcanism thus the Pennsylvanian is not
the only potential source in the region. In the Las Vegas Basin and southern
Sangre de Cristo Mountains, Northrup (1946) and Baltz and Meyers (1989)
described a number of oil shows (lower maturity) there in the Pennsylvanian and
Permian strata. Natural gas potential is more likely given the maturity of
younger, shallower source rocks.
Pennsylvanian and Permian strata from the synorogenic Minturn (AtokanDesmoinesian) and Sangre de Cristo Formation (Missourian-Wolfcampian;
Mallory, 1972b; De Voto, 1980) are predominantly arkosic redbeds with
45
lithologies ranging from coarse conglomerate to shale. Red coloration is typical
of oxidized sediments that tend to have little surviving organic content. It is
doubtful that these formations have thick sealing shales or large traps for oil and
gas generated by the Sandia Formation, but instead allow vertical migration into
traps in the overlying Permian strata, particularly the Glorieta Sandstone that
could be poorly sealed by the Dockum Group.
Potential for occurrence: There have been no reported shows of oil or
flammable natural gas from Pennsylvanian and Permian strata in the vicinity of
the Valle Vidal Unit, but there have been very few wells drilled to test the
potential of these strata. The presence of source rocks is only inferred from
poorly constrained regional paleogeographic information. There is a significant
possibility that if source rocks do exist they are overmature. In a vertical
migration scenario, there are no obvious rocks with excellent sealing lithologies.
These characteristics combined with the obvious lack of interest in drilling
wildcats to test this play in the past forty years suggests that this play would not
see much activity in the coming 20 years. The potential for occurrence cannot
be elevated above “low” at this time.
Potential for development: It is possible that seismic data might be
acquired to attempt to image the strata associated with this play and this should
be considered in the Forest Plan. Otherwise, there is no obvious reason to drill
wells specifically for targeting this play and the development potential is “low”. It
should be noted that El Paso Raton LLC drills water disposal wells to the
Permian. Such a practice would essentially allow a test of this play if one or
more disposal wells were drilled deeper, essentially to the Precambrian
basement.
Table 4.2. Summary of potential for occurrence of oil and gas and development of eastern Valle
Vidal Unit.
Units/
type of play
Raton-Vermejo
Coalbed methane
Pierre-Dakota
Oil and Gas
PennsylvanianPermian
Gas (CO2)
Potential for
occurrence
Potential for
development
High
High
High
Medium
Low
Low
46
Chapter 5 Production Analysis and Estimation
5.1 General characteristics
The objectives of this chapter are to address the following key points: (1) to
analyze current well performance and determine the estimated ultimate recovery
(EUR) and other production characteristics of the Raton Basin play, and (2) to
identify any interference in the production response between wells and thus
qualitatively determine drainage area.
Cumulative gas and water production to May 2003 from the New Mexico
portion of the Raton Basin was 22.1 Bscf (billion standard cubic feet) of gas and
18 million barrels of water, respectively. Figure 5.1 illustrates the trend in
development since the date of first production in October 1999.
Raton Basin CBM Cumulative Production
Time
Water-BBL and Gas-MCF
100,000,000
10,000,000
Cumulative Water
Cumulative Gas
1,000,000
Monthly Water
Monthly Gas
100,000
Apr-03
Feb-03
Oct-02
Dec-02
Jun-02
Aug-02
Apr-02
Feb-02
Oct-01
Dec-01
Aug-01
Jun-01
Apr-01
Feb-01
Oct-00
Dec-00
Jun-00
Aug-00
Apr-00
Feb-00
Dec-99
Oct-99
10,000
Months
256 w ells
200
Cumulative
100
Apr-03
Feb-03
Oct-02
Dec-02
Aug-02
Jun-02
Apr-02
Feb-02
Dec-01
Oct-01
Aug-01
Jun-01
Apr-01
Feb-01
Oct-00
Dec-00
Aug-00
Jun-00
Apr-00
Feb-00
Dec-99
0
Oct-99
No. of Wells
Number of Wells
300
Months
Figure 5.1 Cumulative and monthly gas and water production from all wells in the New Mexico
portion of the Raton Basin, with active wells shown at the bottom. Individual well data production
is available in the Oil and Gas Well Database on the accompanying CD-ROM.
47
It is evident from the increasing number of wells that this pool is currently
undergoing active development. In response to the additional wells, monthly
production has increased until mid-2002 at which time production has remained
constant. Latest monthly production rates (May 2003) are 1.1 Bscf/month and
660,000 barrels of water/month from approximately 260 producing wells.
The production from the Raton Basin in New Mexico can be divided two
areas as shown in Figure 5.2. These individual areas of development are
defined by geological and/or surface restrictions. Individual production plots for
each lease (A, E, C, in northeast area and B, D in southwest area) are shown in
Figures 5.3 through 5.7, respectively. Each figure includes cumulative and
monthly production for gas and water and the active number of wells on a
monthly basis.
48
Figure 5.2 Location map identifying the areas of coalbed methane development northeast and southwest of Vermejo Park (producing wells on
this map are current through 2003).
49
x
Raton Basin (VPR A)
Time
Water-BBL and Gas-MCF
100,000,000
10,000,000
Cumulative Water
Cumulative Gas
1,000,000
Monthly Water
100,000
Monthly Gas
Oct-02
Dec-02
Feb-03
Apr-03
Dec-02
Feb-03
Apr-03
Aug-02
Aug-02
Oct-02
Apr-02
Jun-02
Jun-02
Feb-02
Feb-02
Apr-02
Oct-01
Dec-01
Dec-01
Aug-01
Oct-01
Apr-01
Jun-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Oct-99
Dec-99
10,000
Months
Aug-01
Jun-01
Apr-01
Feb-01
Dec-00
Oct-00
Aug-00
Jun-00
Apr-00
Feb-00
Oct-99
0
Dec-99
No. of Wells
Number of Wells
100
Months
Figure 5.3 Cumulative and monthly gas and water production for VPR (Vermejo Park Ranch) A
wells (central part of northeast producing area, refer to Fig. 5.2 for location) in the New Mexico
portion of the Raton Basin, with active wells shown at the bottom.
50
Raton Basin (VPR B)
Time
Water-BBL and Gas-MCF
100,000,000
10,000,000
Cumulative Gas
1,000,000
Cumulative Water
Monthly Gas
100,000
Monthly Water
Apr-03
Feb-03
Oct-02
Dec-02
Aug-02
Apr-02
Jun-02
Feb-02
Oct-01
Dec-01
Dec-01
Aug-01
Oct-01
Apr-01
Jun-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Dec-99
Oct-99
10,000
Months
Apr-03
Feb-03
Dec-02
Oct-02
Aug-02
Jun-02
Apr-02
Feb-02
Aug-01
Jun-01
Apr-01
Feb-01
Dec-00
Oct-00
Jun-00
Aug-00
Apr-00
Feb-00
Dec-99
0
Oct-99
No. of Wells
Number of Wells
100
Months
Figure 5.4 Cumulative and monthly gas and water production for VPR B wells (eastern part of
southeast producing area, refer to Fig. 5.2 for location) in the New Mexico portion of the Raton
Basin, with active wells shown at the bottom.
51
Raton Basin (VPR C)
Time
Water-BBL and Gas-MCF
1,000,000
Cumulative Water
100,000
10,000
Cumulative Gas
Monthly Water
Monthly Gas
1,000
Feb-03
Apr-03
Oct-02
Dec-02
Aug-02
Apr-02
Apr-02
Jun-02
Feb-02
Feb-02
Oct-01
Dec-01
Dec-01
Aug-01
Apr-01
Jun-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Oct-99
Dec-99
100
Months
Apr-03
Feb-03
Dec-02
Oct-02
Aug-02
Jun-02
Oct-01
Aug-01
Jun-01
Apr-01
Feb-01
Dec-00
Oct-00
Jun-00
Aug-00
Apr-00
Feb-00
Dec-99
0
Oct-99
No. of Wells
Number of Wells
10
Months
Figure 5.5 Cumulative and monthly gas and water production for VPR C wells (eastern end of
northeast producing area, refer to Fig. 5.2 for location) in the New Mexico portion of the Raton
Basin, with active wells shown at the bottom.
52
Raton Basin (VPR D)
Time
Water-BBL and Gas-MCF
100,000,000
10,000,000
Cumulative Gas
Cumulative Water
Monthly Gas
1,000,000
100,000
Monthly Water
Apr-03
Feb-03
Oct-02
Dec-02
Aug-02
Apr-02
Jun-02
Feb-02
Oct-01
Dec-01
Dec-01
Aug-01
Oct-01
Apr-01
Jun-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Oct-99
Dec-99
10,000
Months
Apr-03
Feb-03
Dec-02
Oct-02
Aug-02
Jun-02
Apr-02
Feb-02
Aug-01
Jun-01
Apr-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Dec-99
0
Oct-99
No. of Wells
Number of Wells
100
Months
Figure 5.6 Cumulative and monthly gas and water production for VPR D wells (western part of
the southeast producing area, see Fig. 5.2 for location) in the New Mexico portion of the Raton
Basin, with active wells shown at the bottom.
53
Raton Basin (VPR E)
Time
Water-BBL and Gas-MCF
100,000,000
10,000,000
Cumulative Water
Cumulative Gas
1,000,000
Monthly Water
100,000
Monthly Gas
Feb-03
Apr-03
Oct-02
Dec-02
Aug-02
Apr-02
Jun-02
Feb-02
Oct-01
Dec-01
Aug-01
Apr-01
Jun-01
Feb-01
Oct-00
Dec-00
Aug-00
Apr-00
Jun-00
Feb-00
Oct-99
Dec-99
10,000
Months
Apr-03
Feb-03
Dec-02
Oct-02
Aug-02
Jun-02
Apr-02
Feb-02
Dec-01
Oct-01
Aug-01
Jun-01
Apr-01
Feb-01
Dec-00
Oct-00
Aug-00
Apr-00
Jun-00
Feb-00
Oct-99
0
Dec-99
No. of Wells
Number of Wells
50
Months
Figure 5.7 Cumulative and monthly gas and water production for VPR E wells (western part of
the northeastern producing area, refer to Fig. 5.2 for location) in the New Mexico portion of the
Raton Basin, with active wells shown at the bottom.
A comparison of production statistics by region is shown in Table 5.1. The
most prolific group of wells is in VPR D, where 56% of the cumulative gas
production has occurred as of May 2003. VPR A, which has the highest
percentage of wellbores (37%), has the distinction of producing the highest
cumulative water at 46%. In fact, regions A, C, and E have significantly greater
cumulative water-gas-ratios (WGR) than regions B and D.
A
Date of 1st
production
Oct 1999
No. of
wells
95
Gp
mmscf
6,227
Wp
mBw
8,490
B
Nov 2000
39
2,405
969
62
25
0.40
C
Aug 2002
9
23
154
3
17
6.81
D
Sep 2000
81
12,351
3,576
152
44
0.29
E
Jul 2001
32
1,096
5,116
34
160
4.67
total
256
22,102
18,305
Lease
Table 5.1 Production characteristics for Raton Basin
54
Gp/well Wp/well
mmscf
mBw
66
89
WGR
1.36
5.2 Analysis of single well performance
The Vermejo Formation producing interval consists of a series of thin coal seams
interbedded with sandstone beds. Subsequently, without individual zone tests, it
is only possible to determine production for a well with any accuracy, and not for
a formation or a zone. Furthermore production from many wells is commingled
with the shallower Raton Formation. Table 5.2 provides production statistics for
the Vermejo-only completions and compares the results to the total Raton Basin
play.
Lease
A
No. of
% of
Average
Gp
Vermejo- total
net
mmscf
only
in
perforated (Vermejo
wells
region thickness
only)
Ft
22
23
19
1,605
% of
total
in
region
26
Wp
% of
mBw
total
(Vermejo Vermejoonly)
only in
region
3,569
42
B
30
77
33
2,123
88
875
90
C
0
0
0
0
0
0
0
D
68
84
26
11,546
93
3,123
87
E
1
3
14
48
4
311
6
total
121
47
26
15,322
69
7,878
43
Table 5.2 Production statistics for Vermejo Formation-only completions (excludes wells where
Raton Formation production is commingled with Vermejo Formation production). There are no
Vermejo-only wells in the C Lease. Gp = gas production, Wp = water production, mmscf = million
standard cubic feet of gas, mBw = thousand barrels of water.
A total of 121 wells are completed only in the Vermejo Formation, or 47%
of the total completions to May 2003. These wells contribute 69% of the
cumulative gas production and 43% of the cumulative water production,
respectively. Investigating production from individual leases reveals that a
majority of the gas production from VPR B and D is from the Vermejo Formation,
88 and 93%, respectively. Furthermore, a majority of water production is from
the Raton Formation in VPR A and E, respectively.
A major challenge in evaluating production is to distinguish the
unconventional coalbed methane response from the conventional gas sand
response. Examining the production curves for the existing wells resulted in
identifying four scenarios as shown in Figure 5.8. Type I exhibits the classic
coalbed methane response; i.e., brief, initial high water production followed by a
55
normal decline and initial low gas production which steadily increases to a peak
after some period of time, followed by normal decline behavior. In Type II, the
volume of water production is low with a small to non-existent decline, while the
gas inclines and remains at a stable value (no decline observed). Type III is
similar to Type I except the rate of incline of gas is slower and thus extended.
The final type, IV, exhibits a conventional decline response. In this case, both
gas and water are declining, typically at the same rate.
Production for w ell
Production for well
6000
16000
14000
5000
12000
4000
10000
3000
8000
6000
2000
4000
1000
2000
0
Production for w ell
Gas
Type III
Apr '03
Feb '03
Oct '02
Dec '02
Jun '02
Aug '02
Apr '02
Feb '02
Oct '01
Dec '01
Jun '01
Aug '01
Apr '01
Feb '01
W ater
Apr '03
Feb '03
Type IV
Figure 5.8 Various production behaviors for Raton Basin Wells
Since VPR B and D are adjacent to the Valle Vidal Unit, emphasis was on
analyzing the production response from these wells.
VPR B: As mentioned previously, the majority of wells in VPR B produce
from only the Vermejo Formation. Also, the average water-gas ratio for this
region is low, 0.40, and therefore it is not a major water producer. However, on
examining each well’s performance, a maximum WGR of 2.9 was determined for
a given well. Furthermore, the majority of wells in this region exhibit the type IV
behavior described above, and these wells result in the highest WGRs. Figure
5.9 is a bar graph illustrating the frequency of each type for a given range of
WGR.
56
Dec '02
Oct '02
Jun '02
Gas
Aug '02
Apr '02
Feb '02
Oct '01
Dec '01
Aug '01
Apr '01
Jun '01
Feb '01
Dec '00
May '03
Mar '03
Jan '03
Nov '02
Sep '02
Jul '02
0
May '02
0
Mar '02
5000
Jan '02
10000
500
Nov '01
15000
1000
Sep '01
20000
1500
Jul '01
25000
2000
May '01
2500
Mar '01
Type II
Gas
Production for w ell
30000
Jan '01
Jun '90
W ater
3000
W ater
Aug '90
Apr '90
Feb '90
Oct '89
Dec '89
Aug '89
May '03
Jan '03
Mar '03
Type I
Gas
W ater
Nov '02
Jul '02
Sep '02
May '02
Jan '02
Mar '02
Nov '01
Jul '01
Sep '01
Mar '01
May '01
Jan '01
Nov '00
0
Estimated ultimate recovery (EUR) for a well was determined using
decline analysis of production rate vs. time. Notice, only Types I and IV display
gas decline and therefore can be analyzed. On average, the EUR for Type I and
IV wells is approximately 150 mmscf (million standard cubic feet) of gas. Types
II and III are anticipated to have greater recovery.
5
4
3
frequency
2
1
0
II
>1
.5 - 1
.25 .5
IV
III
Type
I
.125 - < .125
.25
WGR
Figure 5.9 Frequency of the various production types for different WGR in VPR B.
VPR D: VPR D exhibits the lowest WGR of all the regions, and the
highest percentage of wells completed only in the Vermejo Formation. Analysis
of the various production curves resulted in the majority exhibiting either Type II
or IV behavior. Furthermore, a subset of Type IV was identified and is labeled
IV*. This subset follows the general conventional response as described for
Type IV above; however the gas production is significantly greater than the water
production. Figure 5.10 is an example illustrating this behavior.
Production for well
Bbl (Water) and Mcf
(Gas)
14000
12000
10000
8000
6000
4000
2000
Date
Water
Figure 5.10 Example of Type IV* production behavior.
57
Gas
Apr '03
Feb '03
Dec '02
Oct'02
Aug '02
Jun '02
Apr '02
Feb '02
Dec '01
Oct'01
Aug '01
Jun '01
Apr '01
Feb '01
Dec '00
Oct'00
0
An investigation into the WGR for the various production types is shown in
Figure 5.11. For the wells included in the figure, the overall WGR is low,
especially for types II and IV*. However, the wells with the greatest WGR did not
follow any of the identified production trends, but instead have inclining water
behavior and therefore are not included in the figure. The ten wells exhibiting
this behavior account for 25% of the total water production from VPR D. Eight of
those occur immediately adjacent to the outcrop of the Vermejo Formation at the
Vermejo Park Dome and may reflect the influence of direct aquifer recharge, but
we have not data to confirm this possibility. Two are probably due to an
erroneously high data anomaly in the public dataset available (we suspect data
entry error or allocation error). EUR for VPR D wells is much better than VPR B,
averaging 300 mmscf per well.
10
8
6
Frequency
4
2
0
> 1 .5 - 1
.25 - .125
<
.5 - .25
.125
I
II
IV*
IV
III
Type
WGR
Figure 5.11 Frequency of the various production types for different WGR in VPR D.
5.3 Multi-well production response
A log-log plot of rate vs. time developed by Fetkovich (1980) provides the classic
technique to identify if a well is in depletion mode; i.e., has achieved boundary
dominated flow. Figure 5.12 illustrates the type curve generated for matching
production data and determining reservoir and well parameters.
58
Figure 5.12 Log- log plot of rate vs. time (after Sunde et al., 2000)
The objective is to match production data to the depletion stem of the type curve
and therefore be able to estimate drainage area. Due to the limited time these
wells have been producing, (at best 30 to 33 months for leases B and D,
respectively) no discernable match was achieved. Figure 5.13 is an example
illustrating the transient response.
Figure 5.13 Example of a Raton Basin well illustrating limited data for matching.
5.4 Coalbed methane modeling
To interpret the production response a CBM model (Fekete, 2003) was applied to
the data with observed CBM response. Input variables necessary for this
analysis was taken from various sources (Close & Dutcher, 1990; Mavor et al.,
59
1990; Stevens et al., 1992) and are listed in Table 5.3. No matrix shrinkage was
included in this work.
Parameter
Parameter
Parameter
VL = 450 scf/ton
PL = 500 psi
Pabnd = 50 psi
Pi = 600 psi
GC = 250 scf/ton
k = 1-5 md
A = 160 acres
h = variable, ft
Cp = 50x10-6 psi-1
ρb = 1.75 gm/cc
T = 90-115 deg F
φ = <2%
Swi = 100 % (cleat)
Table 5.3 Parameters for CBM model
The objective was to determine original gas-in-place for a generic coalbed
methane well. Based on the above parameters, gas-in-place in VPR B and D is
estimated to be 3 Bscf and 2.4 Bscf, respectively for a quarter section. This
translates to 5 % to 12% recovery using the before-mentioned EURs for VPR B
and D, respectively. To put this in perspective, the Potential Gas Committee in
2000 reports recoveries of 12% for the Fruitland Coal of San Juan Basin and
37% for the Raton and Vermejo Coals of the Raton Basin (including the Colorado
portion). The VPR wells are relatively young in their production cycle and it will
take several more years of production (at minimum) to be able to predict
accurate EURs for these wells based on decline-curve analysis or modeling.
5.5 Summary
Development in the New Mexico portion of the Raton Basin is subdivided into five
leases defined as VPR A, B, C, D, and E. Since VPR B and D are adjacent to
the Valle Vidal Unit, emphasis was on analyzing the production response from
these wells. Results indicate a reduced water-gas ratio (WGR) in VPR B and D
with respect to the rest of the basin.
Production is commingled from numerous coal seams and sand lenses
from both the Vermejo and Raton Formations. Production responses for
individual wells were divided into four categories, several of which exhibit a
coalbed methane type response. However, the most prevalent category
exhibited conventional depletion behavior for water and gas in a low-permeability
formation. This implies a contribution from the sandstones along with the coals.
Estimated ultimate recovery (EUR) was determined for only those wells
that exhibited production decline. On average, these type of wells in VPR D are
60
anticipated to recover 300 mmscf and in VPR B, approximately 150 mmscf,
respectively. These recoveries are minimum values, and do not account for
wells with no decline (Type II and III) or the possibility of a delayed coalbed
methane response beyond the current production time. As can be seen, better
recovery is anticipated in VPR D (by almost double) than in VPR B.
Consequently, development in and adjacent to VPR D is more favorable. This
does not mean that VPR B wells are subeconomic. Analysis could not determine
a typical drainage area for wells in VPR B and D; therefore, results are
inconclusive in support of or against the potential for 80-acre development. Key
factors relevant to not obtaining drainage areas are: (1) the time dependency of
the method to achieve a match for estimating drainage area. Production type
curve matching requires sufficient data to achieve the depletion match and thus
determine drainage volume. In this work, production has occurred for only 30 to
33 months, exhibiting only transient flow conditions and not sufficient time to
determine depletion parameters. (2) aquifer support may mask depletion effects,
and (3) desorption may mask or delay effects.
61
x
Chapter 6 Surface Occupancy and Disturbance
6.1 Approach
Chapter 4 established that the shallowest formations of interest, the Vermejo and
Raton Formations, have the highest potential for resource occurrence and
development. The RFDS anticipates that development would begin with an initial
test drilling phase where some (perhaps 5 to 10) wells would be drilled and
tested to confirm resource potential and then subsequently completed as
producers once infrastructure is available. It is believed that all available 160acre equivalent coalbed methane subsurface reservoir cells would be developed
within the 20–year duration of the RFDS. A subsurface reservoir cell is the term
used here to describe the 3-dimensional reservoir volume that statutory
regulations allow an operator to drain with one vertical or near-vertical deviated
well. A cell will usually have a square 160-acre surface projection with a drilling
“window” for a vertical-well pad to be placed near the center of this area. With
regulatory approval, irregularly-dimensioned cells may have an irregular
projection at the surface. Depending upon if, and when, downspacing might
occur during the 20-year life of the RFDS (an event we cannot predict or assign a
probability to) some or all of 80-acre equivalent infill (reduced density) cells could
be added. Deeper, non-CBM targets are possible, but these could be tested as a
consequence of drilling deeper for the purpose of disposing of water produced by
the shallow CBM play. The approach taken in Chapter 6 is to estimate the
number of feasible subsurface completions (one in each cell for vertical wells)
that would be desirable under a full development scenario and then estimate the
surface disturbance area associated with these completions.
Not all subsurface completions cause additional surface locations (well pads)
to be constructed. For example, there are savings in terms of number of surface
locations if water disposal wells and deep tests can be placed on pads that also
accommodate producing CBM wells. There are also potential savings in the
number of surface locations if directional drilling should prove economically
feasible in the 20-year term. At present we believe that it is currently not
economically feasible for highly deviated (or horizontal) wells to be constructed
for cell drainage, otherwise this technique would be applied today at the Vermejo
Park Ranch where such technology could be beneficial. We cannot predict if and
when such well tech technology (which certainly currently exists but is very
expensive) might become economically feasible. However, we acknowledge that
it could become potential to do so within a 20-year time frame.
On a total acreage-only basis, if the entire 40,000-acre eastern Valle Vidal
Unit were available for development on 160-acre spacing of surface locations for
vertical wells, and irregular well placement was allowed for by regulatory
approval, there would be 250 reservoir cells available for producing wells. This
assumes that the coalbed methane resource is minimally (but sufficiently)
62
economic using lowest-cost vertical wells. It is not the purpose of this RFDS to
cause withdrawals of acreage associated with the surface expression of these
cells for any reasons other than geologic and customary statutory reasons. Any
subsequent analyses by the Carson National Forest would examine interaction
and potential conflicts of the development described here on other resources and
in terms of overall environmental impacts. Figure 6.1 illustrates the surface
projection of 191 subsurface reservoir cells which could be accessed by vertical
or slightly deviated wells. This reduced number of accessible cells (from 250) is
predicted based on two limiting factors: statutory and geologic. Figure 6.1 was
constructed assuming only full 160 acre quarter section surface projection
(surface locations) per cell. There are a number of “slivers” of land less than
square 160 acres along the boundaries of the area that would normally not be
drilled under standard spacing and well location rules. Many of these slivers,
particularly along the western and southern boundaries, are also not conducive
to physical occupation due to topography (e.g. cliffs, canyon walls). This
withdrawal reduces the number of reservoir cells that could be accessed by
standard vertical wells by 21. In addition, it is believed that fractured igneous
intrusions (dikes) would channel water to producing wells and be undesirable
neighbors to wells. A ¼ mile buffer was drawn around intrusions. 160-acre
quarter sections that have more than 40 acres covered by the buffer were
withdrawn reducing the number of reservoir cells/surface locations able to be
occupied by standard vertical wells by another 38. A 300 ft buffer was placed on
two major access roads 1914 and 1950 for illustration purposes only.
Of the 191 subsurface reservoir cells remaining, it is clear that some cannot be
occupied at the surface due to topography based on rules that require a narrow
window for well placement at the center of the quarter section. This is
particularly true along the western and north-central margins of the eastern Valle
Vidal Unit. However, no withdrawal of area was applied to those locations
because flexible well location rules, combined with deviated (not horizontal)
drilling, could make those reservoir cells accessible. Again, it is assumed that
deeper wells will be drilled with the dual purpose of water disposal and testing
deeper plays. These wells can be placed on a pad with a shallow well, but the
surface footprint of the pad would cover a larger area.
63
Figure 6.1 Map showing estimated minimum number of well locations for vertical wells for draining subsurface
reservoir cells estimated to be likely for coalbed methane development in the eastern Valle Vidal Unit. To our
knowledge, highlighted roads 1950 and 1914 are the only roads currently open for public access.
64
6.2 Surface well locations
A square-mile section equals 640 acres of surface area. Four, 160- acre vertical
well locations can be placed in each section. Based on the approach outlined in
section 6.1, a minimum of 191 surface locations would be required to fully
develop the coalbed methane resource on of the eastern Valle Vidal Unit using
vertical wells at 160-acre per well spacing. A surface location (well pad) is an
area of land that is cleared and leveled to provide an area for temporarily
accommodating, moving and storing large equipment for purposes of
construction and maintenance of wells. Once wells are constructed, the area
required for maintenance can be substantially less than that needed during the
drilling and completion stages of construction. This is discussed further below.
An estimated four, deep, vertical, produced-water disposal wells will be
required based on statutory regulations and operator practices on the Vermejo
Park Ranch. These wells will not cause additional surface locations because
they can be “twinned” on pads with producing wells, but the area of disturbance
will be larger for surface locations that also accommodate disposal wells.
At this time, it is not anticipated that drainage of multiple subsurface reservoir
cells will be economically achieved by drilling horizontally. The additional costs
associated with horizontal drilling vary greatly depending upon the target the
operator is trying to hit, the degree of accuracy that is required (the window of
error) to hit the target, depth, reach (distance to terminus) of the well from drill
pad, drilling methods (air, mud, foam, coiled tubing, etc.), availability of
appropriate equipment, and transportation costs among others. We do not
believe that this play is appropriate for horizontal drilling technology. This is due
to the shallow depth of the CBM play, thin coal beds separated vertically over
hundreds of feet (multiple targets), and potentially long horizontal reach.
6.3 Lease infrastructure
Lease infrastructure required includes natural gas- and water handling-related
facilities and access roads. Natural gas infrastructure includes a trunk pipeline
for transporting gas to market, a central compressor facility for compressing
lease gas to required pipeline pressures, a gathering pipeline system that
branches to the individual wells, and well pad equipment including wellheads and
wellhead separators. It is assumed that the trunk pipeline would enter the
property from the east, either connecting to the existing El Paso pipeline or
following the right of way for Forest Road 1950 to connect to a pipeline
paralleling Highway 64. Gas gathering pipelines could be laid beside access
roads to individual wells. The central gas compression facility could be powered
by combustion of lease gas or by electricity (the power source used at the
Vermejo Park Ranch). If electricity is used, a power line would need to be strung
or buried along the right of way accommodating the trunk gas pipeline.
65
Water handling-related infrastructure includes pump jacks to remove water
from wells, flow lines to deliver water from wells to a storage tank battery,
filtration equipment, injection pumps, and water disposal wells. Pump jacks
could be powered by lease gas or by electricity (they are powered by electricity at
the Vermejo Park Ranch). As many as four disposal sites may be required, each
equipped with tanks and equipment houses. Flow lines between wells and
disposal facilities can follow well access roads along with gas gathering lines.
Electric lines, if used, could be strung or buried beside flow lines (lease power
lines are buried at the Vermejo Park Ranch). .
6.4 Footprint of drilling and production operations
The surface disturbance normally associated with drilling and production
operations is two acres per well pad plus an additional acre of right-of-ways for
associated roads and pipelines. For 191 surface locations, this is 573 acres.
Water disposal and central compression facilities would expand the footprint of a
limited number of locations. Four water disposal facilities and one compressor
site each having 3 acres of added area contribute an additional 15 acres for a
total infrastructure disturbance of 588 acres. Additional surface disturbance
would result if right-of-ways are not limited to roadways or if roadways are not
placed optimally to reduce total surface area.
Of course the footprint of drilling and production operations is variable
dependent upon the needs of the operator and the mutual goals set by the
operator and land owner/manager. There are certainly alternative scenarios that
could apply to the eastern Valle Vidal Unit. It is not the purpose of this RFDS to
determine specific environmental impact of oil and gas operations, yet there are
some obvious development alternatives that the land management agency could
consider relative to oil and gas production options. The authors would
encourage the Carson National Forest to consult with both the operator and
surface owner of the Vermejo Park Ranch wells to consider potential working
alternatives to standard oil and gas development practices. At the Vermejo Park
Ranch, well pads have a much smaller (than standard) surface footprint, greatly
reduced visual impact, reduced exhaust emissions, and reduced environmental
impact overall due to specially negotiated conditions on timing and method of
operations. As example, well locations take up only 0.5 acres. Roadways and
right-of-ways are combined to a 30 ft wide path, but right-of-ways are
immediately reclaimed to reduce the path to 20 ft. These measures alone reduce
the surface disturbance attributable to individual wells by almost two-thirds. As
described above, the assumption made to determine surface disturbance
associated with individual well completions in this RFDS is the standard 2 acres
per well pad plus an additional 1 acre of right-of-ways for associated roads and
pipelines.
66
Chapter 7 Responses to Operator Survey
7.1 Summary of responses
The objective of the industry survey (example in Appendix 1) was to solicit
informed opinions from coalbed methane operating companies and other
companies familiar with the Raton Basin. See Chapter 2 for the methods
applied. Four responses were provided; three were from coalbed methane
operators in the Raton Basin. The following list of base assumptions was
provided to the operators:
•
•
•
There is a “shallow” (generally less than 2000 feet depth) petroleum system
play that yields coalbed methane from coal and sandstone beds in the Raton
and Vermejo Formations in the Raton Basin. Much or all of the RFD study
lies within a moderate to high probability area for production from this
system. Exploration and production activity associated with this play will
dominate the RFD scenario.
There is a “mid-depth” (generally between 2000 feet and 8000 feet depth)
petroleum system play that could yield oil or natural gas from Mesozoic
sandstone and shale formations ranging from the Trinidad Sandstone to the
Morrison Formation. There has been no commercial production to date from
this system, but the number and quality of oil and gas shows from these
formations suggests that the play would be an attractive target for future
exploration, conducted through drilling of wildcat wells. The RFD scenario
will consider a limited number of such wells.
There is potential for a “deep” (generally greater than 8000 feet depth) play in
Paleozoic rocks that may cause seismic exploration activity to be conducted
with the possibility of one or more exploratory wells.
The Following questions were asked. Responses are noted.
7.1.1 Do you agree with the base assumptions?
YES: 4
NO: 0
7.1.2 Do you currently operate CBM wells in the Raton Basin?
YES: 3
NO: 1
7.1.3 Do you currently operate CBM wells in other basins but not Raton Basin?
YES: 2
NO: 1
No response: 1
x
67
7.1.4 Current CBM well spacing in the Raton Basin is 160 acres per well.
Considering the 20-year timeframe of the RFD, do you anticipate an increase in
well density to 80 acre spacing?
YES: 3
NO: 1
7.1.5 Current CBM wells in the Raton Basin are vertical wells. Do you anticipate
horizontal drilling becoming a viable option for such shallow reserves in the
coming 20 years?
YES: 1
NO: 3
7.1.6 Noise and exhaust emissions from production and transportation
equipment could be a critical consideration for allowing/denying development.
On the Vermejo Park Ranch, buried electric power is used to run pumpjacks,
compressors, and other motors. Would you consider this to be an acceptable
alternative to lease-gas powered equipment if necessary?
YES: 2
NO: 2
Additional comment from one respondent stated “terrain too rugged-would also
limit economic viability. Current technology can reduce noise and exhaust
emissions to acceptable limits.”
7.1.7 What gas compression option would you prefer for this type of production?
Wellhead:
0
Centralized: 4
7.1.8 What water disposal options would you prefer for produced water less than
2000 ppm total dissolved solids?
Surface disposal: to settling pits, then to natural drainages:
4
Subsurface injection into deep saline aquifers:
0
Trucking (at minimum 30 miles) to off-site approved disposal facilities:
0
7.1.9 If productive, mid-depth Mesozoic targets will most likely yield gas with
producing wells spaced 320 acres per well.
YES: 2
NO: 2
Additional comments from two respondents with NO answer: “Shale gas potential
may require wells closer than 320s to drain the tight gas source” and “160 acres
required as would be tight gas”
7.1.10 Seismic exploration methods in the area will likely be:
2-D: 0
3-D: 4
68
Probable spacing between lines/cross-lines: One respondent replied “~1000 ft”.
Another respondent replied “900 ft shot lines, 300 ft receiver lines, but use
existing roads as much as possible”.
7.2 Implications of responses to RFDS
The survey responses generally support the base assumptions presented to the
respondents with some exceptions.
In question 7.1.4, three of four respondents favored 80-acre well spacing
for development. We do not have enough data to demonstrate a need for 80acre spacing at this time. Justification for infill drilling to this density would need
to be supported by modeling and analysis of more years of production than are
available in wells adjacent to the eastern Valle Vidal Unit. The degree of
stratigraphic complexity of the Vermejo and Raton Formations does suggest to
us that evaluation of 80-acre well spacing might be justified at some point in the
future when sufficient production data is available. We provide two scenarios in
the RFDS, one based on 160-acre and 80 acres well spacing.
In question 7.1.8, all of the four respondents preferred a surface discharge
option for produced waters. The Carson National Forest is encouraged to
consider a surface discharge option as part of any further analysis of field
development. Currently the State of New Mexico requires subsurface disposal for
produced waters.
69
x
Chapter 8 Impacts of future technology
8.1 Technology impacts on the RFDS
Advances in technology and research have played an important role in improving
gas recovery from unconventional plays of the Rocky Mountain region. Several
key areas likely to impact Raton Basin development are directional/horizontal
drilling, well stimulation, and the remediation of produced water. Each of these
may eventually have an impact on development of the eastern Valle Vidal Unit.
The technologies listed below, if successfully applied to the Raton Basin, could
increase the economic viability of production of individual wells and/or increase
the effectiveness of draining reservoirs as a whole. However, given the current
level of deployment, these technologies are not considered to be alternative
scenarios to that recommended in the conclusions of this RFDS, but rather
potentially desirable future possibilities.
8.2 Directional and horizontal drilling
The objectives of directional (purposely deviated) and horizontal drilling are
typically related either to avoiding surface occupation or to increasing production
efficiency. These two objectives are not always compatible. Avoidance of
surface occupancy is typically due to topographic or environmental concerns. In
this case, a drilling location will be selected as near as possible to the subsurface
target and a well bore will be constructed in such a manner as to minimize cost
while achieving the subsurface target. The goal is to capture the same reserves
that would have been achieved from a vertical well, had one been drilled. In
terms of economic efficiency, such wells are less efficient due to increased cost
(approximately 20%) and higher operating expenses with no change in
producible reserves. Such wells can present difficulties in operation, particularly
when artificial lift is required because inexpensive rod pumps (driven by
pumpjacks) cannot operate when the borehole has “doglegs” or bends.
Application of horizontal well technology in the onshore United States has
been increasing in recent years. For example, horizontal well activity in the San
Juan Basin has increased lately in the Fruitland Coal, as industry realizes the
benefits of such practices. However, not all reservoirs are candidates for this
type of completion. A first step in selecting appropriate reservoirs is to screen
the key parameters for commercial success. For example, natural fracture
orientation and intensity, net pay and vertical permeability, susceptibility to
formation damage, reservoir pressure, anisotropy, and drilling/completion costs
need to be understood in the context of penetrating the reservoir with a horizontal
well.
70
Fractured reservoirs such as coals may be more suitable for horizontal drilling
because of the ability to intersect fractures (cleats). However, where artificial lift
is required, this drilling technology often proves impractical. We believe that the
thin and discontinuous coalbeds in the eastern Valle Vidal Unit, and the relatively
low net coal existing over a large gross vertical interval, are conditions that are
not conducive to horizontal drilling. The shallow depth of the CBM reservoir
would make horizontal well construction excessively expensive compared to
vertical wells. We do not recommend horizontal drilling as a viable method during
the 20-year life of the RFDS.
8.3 Completion technology
Hydraulic fracture techniques have evolved over the years with improvements in
fluids, proppants, and design. Hydraulic fracturing is achieved by pumping large
volumes of fluid (typically fresh water or a fresh water-nitrogen-soap foam), under
pressure, with viscosifying additives (guar gum is typical) and quartz sand. The
purpose is to cause the formation of interest to fracture under pressure, with the
sand propping open the fractures to allow reservoir fluids to flow through the
newly opened conduits. Advances in hydraulic fracturing of low permeability
formations will have, perhaps, the greatest potential impact on future
development; particularly, to improve the effectiveness in thin, multiple pay
zones. Currently identified issues that require further improvement are:
•
•
•
•
•
Cost reduction of all stimulations is a priority among all operators. The
goal is to increase fracture efficiency while reducing cost per application in
future well completions.
Research is required to achieve more effective hydraulic fracturing of
naturally under-pressured or semi-depleted formations.
There is currently a need to improve multi-zone or multi-formation
stimulations within a single well bore.
All stimulations tend to cause some degree of formation damage (pore
network plugging) such that the efficiency of the stimulation is less than
ideal; therefore there is a need for better identification of sensitivity of
formations to fluid interaction-related damage and need for research into
optimal, non-damaging fluid systems
There is a regional shortage of availability of better-engineered liquefied
CO2 delivery systems. This limits the application of, and increases the
cost of, less damaging liquid CO2 fracturing.
Hydraulic fracturing techniques were applied to all wells that are currently
producing gas at the Vermejo Park Ranch. This stimulation technique appears to
be a critical element in economic production of the CBM reservoir. There,
economic improvements in a 20-year time frame would likely result from
improved stimulation methods.
71
8.4 Produced water treatment and filtration
Production of formation water is a necessary requirement for production of
coalbed methane. Much of the gas content of coals is in the form of molecules of
methane physically adsorbed on organic particles in the coal matrix. By
producing formation water from the coal porosity system, formation pressure is
reduced. Reduction of formation pressure is the primary mechanism for the
desorption of methane from the coal matrix. Water produced as a byproduct of
pressure reduction cannot be disposed of by returning it back into the formation
from which it was produced because this would replenish the pressure and halt
the production process. Therefore, produced waters must be disposed of in an
approved fashion. Generally, this can be done by surface discharge if the water
quality is suitable, or disposal by injection into a deep disposal zones if the water
quality is poor, however, requirements differ according to State regulation. In the
Colorado part of the Raton Basin, produced waters of sufficient quality are
pumped to a surface pit for settling of coal fines, then transferred to surface
drainages, adding volume to larger rivers. In New Mexico, Raton Basin produced
water is required to be injected into state-approved deep disposal zones.
An argument can be made that discharge to the surface allows water of
acceptable quality to be reused by adding to local stream flow. There may be
beneficial uses of the water downstream in agriculture, manufacturing, and
municipal applications. However, if fresh water is pumped into a saline aquifer
for disposal, it is essentially permanently removed from reuse and thus wasted.
Water produced at the Vermejo Park Ranch is best classified as brackish, in
the range of 2,000 to 10,000 mg/l total dissolved solids. Current methods to
improve the quality of brackish water for beneficial use tend to be excessively
expensive compared to the option of deep saline aquifer injection. There are
many ongoing collaborative research efforts underway in New Mexico and
elsewhere to produce useable, even drinkable water from brackish aquifers. One
pilot project seeks to aid the City of Alamogordo and Holloman Air Force Base by
adding significantly to the drinking water supply through application of innovative
filtration technology (Allan Sattler, Sandia National Laboratories, 2003, pers.
comm.). Another effort being conducted by Sandia National Laboratories, New
Mexico Institute of Mining and Technology, and others is focusing on chemical
treatment of coalbed methane produced waters in the San Juan and Raton
Basins. An initial conclusion of the water quality evaluation stage of that project
is that some Raton Basin produced waters already meet EPA surface discharge
requirements. Those that do not meet discharge requirements would qualify with
minimal treatment.
As stated above, it is not the purpose of this RFDS to determine specific
environmental impact of oil and gas operations. There are, however, obvious
72
development alternatives that further analysis should consider relative to optional
oil and gas operation methods. Given a supportive regulatory environment and
growing commercial availability of treatment and filtration technology already
available, produced water could be effectively and economically improved at
either the wellhead or at centralized facilities to meet reasonable requirements
for a surface discharge option in the eastern Valle Vidal Unit should that option
be found desirable. A surface discharge option for produced water would not
significantly reduce the footprint of coalbed methane operation if a leasecentralized treatment facility would be required, such a facility being similar in
size to a subsurface disposal facility. It is important to note that as the coalbed
aquifer is depleted over time, the volumes of water being produced will likely
decrease.
73
x
Chapter 9 Conclusions: Reasonable Foreseeable Development Scenario
9.1 Potential for occurrence: High
The overall potential for occurrence of oil and gas resources in the eastern Valle
Vidal Unit is high using the ranking method described in this report. This rank is
based on geologic conditions predicted to be present at the site relative to that of
adjacent lands being actively and economically developed. The primary play of
interest is the areally-extensive, shallow (less than 2000 ft deep) coalbed
methane and low permeability sandstone natural gas play associated with the
Vermejo and Raton Formations. There is some uncertainty as to the quality and
economics of this play due to lack of coal quality data in the southern part of the
study area. However, there is no negative evidence. The potential for igneousinfluenced, increased coal maturity in this area is encouraging.
Another high potential occurrence play using the ranking method described in
this report is the fractured “shale” blanket-type Pierre-Dakota play. There is also
a lesser possibility of conventional reservoir traps in the Dakota Sandstone. A
third play based on postulated presence and source rock potential of the
Pennsylvanian Sandia Formation is assigned a low potential due to uncertainty
and lack of positive indicators such as oil or gas shows nearby.
9.2 Potential for development: High
The potential for development of oil and gas resources at the eastern Valle Vidal
Unit is high based on the ranking scheme described in this report. If allowed to
lease the eastern Valle Vidal Unit, oil and gas operators will be primarily
interested in the immediate economic benefit of developing the coalbed methane
resources. Development will proceed from an initial phase of testing 5 to 10
selected sites to evaluate geologic and economic conditions, primarily gas-inplace and net coal thickness in the Vermejo Formation for comparison with
productive gas wells on the adjacent Vermejo Park Ranch. A second phase will
focus on bringing in the proper infrastructure to produce the area as a whole.
This phase involves construction of a pipeline that will require negotiation to be
successful and therefore not evaluated here as to economic feasibility. Other
infrastructure development will be gas compression and water handling and
disposal facilities. A third phase will involve drilling every allowed location on 160
acre spacing where feasible using conventional vertical drilling technology. A
fourth phase might involve drilling problematic locations using deviated (not
horizontal) wellbores if economics prove to be sufficient. Deep targets will be
tested as a side benefit of drilling water disposal wells and may not require
additional locations.
74
x
9.3 Drilling activity and surface use forecast
Development of the coalbed methane resource is not likely to require reflection
seismic data. Evaluation of deeper plays would benefit from such data.
Operators in the region have expressed interest in 3-D seismic data with
lines/cross-lines spaced closer than ¼ mile. No evidence of existence of 3-D
seismic data or current acquisition activity was found in the vicinity. If acquired
later in the RFDS, seismic acquisition by vibroseis source (trucks) may be able to
take advantage of existing lease roads to minimize disturbance.
Over the 20 year life of the RFDS, it is predicted that a minimum of 195 total
wells would be drilled on a total of 191 surface locations at 160-acre per well
spacing. Four wells will be drilled as water disposal wells/deep tests and could
be placed on an existing well pad for a shallow coalbed methane well. The area
of disturbance for each location need not be large because the shallow depth
and minimal required equipment would allow for small locations. Innovative and
environmentally progressive development practices could significantly reduce
impacts to alternative land uses while promoting maximum economic benefit.
Flexibility in spacing rules and better-than-anticipated geologic conditions could
allow expansion to a total of 254 wellbores on 250 surface locations.
Approval for 80-acre infill (increased density) drilling locations may be needed
to produce the resource within the 20-year time frame. Presently there is
insufficient evidence to determine the possibility that downspacing will occur.
Some operators believe that there will eventually be sufficient justification for this.
If 80-acre per well spacing is approved, this would essentially double the number
of locations. Therefore, a range of between 191 and 500 surface locations (well
pads) is possible within the 20-year life of the RFDS.
Coalbed methane plays benefit from planned dewatering of coal over a large
area. If the Carson National Forest allows oil and gas leasing and development,
it is worth considering leasing the eastern Valle Vidal Unit as a contiguous block
of acreage in order to drain the natural gas reserves most efficiently,
economically, with the least disturbance, and to prevent duplication of
infrastructure.
x
75
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81
Appendix 1
Industry Survey of Exploration and Development in the Valle
Vidal Unit, Carson National Forest, Colfax County, New
Mexico
The Carson National Forest (NFS) has requested from New Mexico Tech an estimation
of the Reasonable Foreseeable Development (RFD) for the eastern Valle Vidal Unit,
Colfax County, New Mexico. The study begins with an effective date of January 1, 2005
with a duration of 20 years. The RFD characterizes potential oil and gas resources,
describes options for subsurface development needed to access and drain reservoirs, and
estimates the probable surface disturbance that would result from subsurface
development. The final RFD will be used to support an environmental analysis through
an Environmental Impact Statement (EIS) that will lead to a leasing decision and amend
the Carson National Forest’s Forest Plan. Industry’s participation is solicited to better
develop a plan that is mutually beneficial to all concerned.
Description of study area
The eastern Valle Vidal Unit is located approximately 24 miles northwest of Cimarron,
New Mexico and 17 wiles east of Costilla, New Mexico in the Sangre de Cristo
Mountains on Forest System Road 1950. The area of study encompasses 40,000 acres
within the Forest Service boundary east of a linear geologic feature (an igneous dike)
called the Rock Wall. The area falls within the geologic boundaries of the Raton Basin, a
region of current coalbed methane (CBM) development activity.
Summary of current management and oil and gas development of the Valle Vidal
Unit
Prior to 1999, there was no commercial oil or gas production from the New Mexico part
of the Raton Basin. From 1999 to May, 2003 some 256 wells have been drilled that
produce CBM at the Vermejo Park Ranch in Colfax County, New Mexico. The Vermejo
Park Ranch is adjacent to the northern and eastern boundary of the Valle Vidal Unit.
Currently there is no oil or gas production from the Valle Vidal Unit. In addition, there is
Appendix 1, page 1
no infrastructure (pipelines, electric power) other than access roads to support production.
Historically, exploration there has been limited to drilling to evaluate the coal and water
resources. The federal oil and gas (including CBM) mineral estate encompassed by the
Valle Vidal Unit is not currently leased. Recent adjacent coalbed methane development
coupled with industry requests for leases has prompted the Carson National Forest to
consider amending the Forest Plan to include oil and gas development.
Development potential base assumptions
The following list of general constraints is provided as a baseline for answering the
following questions.
•
There is a “shallow” (generally less than 2000 feet depth) petroleum system play that
yields coalbed methane from coal and sandstone beds in the Raton and Vermejo
Formations in the Raton Basin. Much or all of the RFD study lies within a moderate
to high probability area for production from this system. Exploration and production
activity associated with this play will dominate the RFD scenario.
•
There is a “mid-depth” (generally between 2000 feet and 8000 feet depth) petroleum
system play that could yield oil or natural gas from Mesozoic sandstone and shale
formations ranging from the Trinidad Sandstone to the Morrison Formation. There
has been no commercial production to date from this system, but the number and
quality of oil and gas shows from these formations suggests that the play would be an
attractive target for future exploration, conducted through drilling of wildcat wells.
The RFD scenario will consider a limited number of such wells.
•
There is potential for a “deep” (generally greater than 8000 feet depth) play in
Paleozoic rocks that may cause seismic exploration activity to be conducted with the
possibility of one or more exploratory wells.
Confidentiality Statement
Information gathered in this survey to be used solely by New Mexico Tech for the
purposes of the RFD and the identity of the person or company responding to the survey
will not be disclosed to or used by any other party.
Appendix 1, page 2
Survey
Please answer each question below by circling your choice. Please feel free to attach a
narrative answer or further discussion on a separate sheet.
Question 1: Do you agree with the base assumptions?
YES
NO (important to attach a narrative explanation).
Question 2: Do you currently operate CBM wells in the Raton Basin?
YES
NO
Question 3: Do you currently operate CBM wells in other basins but not Raton
Basin?
YES
NO
Question 4: Current CBM well spacing in the Raton Basin is 160 acres per well.
Considering the 20-year timeframe of the RFD, do you anticipate an increase in well
density to 80 acre spacing?
YES
NO
Question 5: Current CBM wells in the Raton Basin are vertical wells. Do you
anticipate horizontal drilling becoming a viable option for such shallow reserves in
the coming 20 years?
YES
NO
Question 6: Noise and exhaust emissions from production and transportation
equipment could be a critical consideration for allowing/denying development. On
the Vermejo Park Ranch, buried electric power is used to run pumpjacks,
compressors, and other motors. Would you consider this to be an acceptable
alternative to lease-gas powered equipment if necessary?
YES
NO
Question 7: What gas compression option would you prefer for this type of
production?
A) Wellhead
B) Centralized
Question 8: What water disposal options would you prefer for produced water less
than 2000 ppm total dissolved solids?
A) Surface disposal: to settling pits, then to natural drainages
B) Subsurface injection into deep saline aquifers
C) Trucking (at minimum 30 miles) to off-site approved disposal facilities
Appendix 1, page 3
Question 9: If productive, mid-depth Mesozoic targets will most likely yield gas with
producing wells spaced 320 acres per well.
YES
NO
Question 10: Seismic exploration methods in the area will likely be:
A) 2-D
B) 3-D
Probable spacing between lines/cross-lines:____________________
We would appreciate any further comments or suggestions pertaining to future
development plans.
Name:
Company:
Confidentiality Statement
Information gathered in this survey to be used solely by New Mexico Tech for the
purposes of the RFD and the identity of the person or company responding to the survey
will not be disclosed to or used by any other party.
Return Survey to:
Brian Brister
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, NM 87801
Ph: 505-835-5378
Fax: 505-835-6333
Email: bbrister@gis.nmt.edu
Appendix 1, page 4
Appendix 2
Raton Basin Bibliography
Abbott, P. O., Geldon, A. L., Cain, D., Hall, A. P., and Edelmann, P., 1983,
Hydrology of area 61, northern Great Plains and Rocky Mountain coal
provinces, Colorado and New Mexico: United States Geological Survey,
Open File Report 83-132, 99 p.
Ambrose, W. A., Tyler, R., Scott, A R., and Kaiser, W., 1992, Coalbed methane
potential of the greater Green River, Piceance, Powder River, and Raton
Basins: American Association of Petroleum Geologists Bulletin, v. 76, no.
8, p. 1255.
Anonymous, 1993, Quarterly Review of Methane from Coal Seams Technology,
Raton Basin, Colorado and New Mexico: Methane from Coal Seams
Technology, (August issue), p. 33-36.
Anonymous, 1999, New Mexico Raton Basin coalbed methane development: Oil
and Gas Journal, v. 97, no. 17, p. 50.
Baltz, E. H., 1965, Stratigraphy and history of Raton Basin and notes on San Luis
Basin, Colorado-New Mexico: Bulletin of the American Association of
Petroleum Geologists, v. 49, no. 11, p. 2041-2075.
Baltz, E. H., and Myers, D. A., 1999, Stratigraphic framework of upper Paleozoic
rocks, southeastern Sangre de Cristo Mountains, New Mexico, with a
section on speculations and implications for regional interpretation of
Ancestral Rocky Mountains paleotectonics: New Mexico Bureau of
Geology and Mineral Resources, Memoir 48, 269 p.
Bauer, P. W., Lucas, S. G., Mawer, C. K., and McIntosh, W. C., 1990, Tectonic
Development of the Southern Sangre de Cristo Mountains, New Mexico:
Socorro, New Mexico Geological Society, 450 p.
Billingsley, L. T., 1977a, Stratigraphy and clay diagenesis of the Trinidad
Sandstone and Vermejo Formation, Walsenberg area, Colorado:
Amercian Association of Geologists Bulletin, v. 61, no. 8, p. 1372.
Billingsley, L. T., 1977b, Stratigraphy of the Trinidad Sandstone and associated
formations, Walsenberg area, Colorado, in Veal, H. K., ed., Exploration
Frontiers of the Central and Southern Rockies: Rocky Mountain
Association of Geologists, Field Trip and Conference Guidebook, p. 235246.
Bland, D. M., 1992, New Mexico's Coalbed Methane Industry: New Mexico
Appendix 2, page 1
Energy, Minerals and Natural Resources Department, Mining and
Minerals Division, Mine Registration and Geological Services, 6 p.
Carlton, D., and Cornelius, C., 2000, Macro geologic controls on coalbed
methane resource development; Raton Basin, S.E. Colorado, USA: AAPG
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Carter, D. A., 1956, Coal deposits of the Raton Basin, in McGinnis, C. J., ed.,
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Cather, S. M., 2004, Laramide Orogeny in central and northern New Mexico and
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Geology of New Mexico, Volume 1: New Mexico Geological Society,
Special Publication, in press, preprint available at:
http://geoinfo.nmt.edu/staff/cather/papers/Cather_Laramide_2002.pdf
Cheney, R. S., 1982, Geophysical Investigation of the Raton Basin [Master's
thesis]: Texas Tech University, 75 p.
Close, J. C., 1988, Interpretation of vitrinite reflectance data for the Raton Basin,
Southern Colorado -northern New Mexico: Geological Society of America,
Abstracts with Programs, v. 20, no. 7, p. 91.
Close, J. C., 1988, Coalbed Methane Potential of the Raton Basin, Colorado and
New Mexico [Doctoral thesis]: Southern Illinois University, 432 p.
Close, J. C., 1993, Processess and timing of thermal maturation in the Raton
Basin, Colorado and New Mexico, in 1993 International Coalbed Methane
Symposium: Society of Petroleum Engineers, Birmingham, AL, p. 383393.
Close, J. C., and Dutcher, R. R., 1990, Prediction of permeability trends and
origins in coal-bed methane reservoir of the Raton basin, New Mexico and
Colorado, in Bauer, P. W., Lucas, S. G., Mawer, C. K., and McIntosh, W.
C., eds., Tectonic Development of the Southern Sangre de Cristo
Mountains, New Mexico: New Mexico Geological Society 41st Annual Field
Conference Guidebook, p.387-395.
Close, J. C., and Dutcher, R. R., 1991, Update on coalbed methane potential,
Raton Basin, Colorado and New Mexico: Society of Petroleum Engineers,
SPE20667, 16 p.
Close, J. C., and Dutcher, R. R., 2000, Geomorphology of drainage patterns:
clues to coal gas natural fracture timing, orientation and location, Raton
Basin, Colorado-New Mexico, in Schwochow, S. D. and Nuccio, V. F.,
Appendix 2, page 2
eds., Coalbed Methane of North America II: Rocky Mountain Association
of Geologists, p. 25-48.
De Voto, R. H., 1980, Pennsylvanian stratigraphy and history of Colorado, in
Kent, H. C., and Porter, K. W., eds., Colorado Geology: Rocky Mountain
Association of Geologists, p. 71-101.
Dolly, E. D., and Meissner, F. F., 1977, Geology and gas exploration potential,
upper Cretaceous and lower Tertiary strata, northern Raton Basin,
Colorado, in Veal, H. K., ed., Exploration Frontiers of the Central and
Southern Rockies: Rocky Mountain Association of Geologists, Field Trip
and Conference Guidebook, p. 247-270.
Ewing, R. C., and Kues, B. S. 1976, Guidebook of Vermejo Park Northeastern
New Mexico: Socorro, NM, New Mexico Geological Society, 303 p.
Fleming, R. F., 1987, Paleoenvironmental significance of fossil chlorococcalean
algae from the Raton Formation, Colorado and New Mexico: Geological
Society of America, Abstracts with Programs, v. 19, no. 5, p. 275.
Flores, R. M., 1987, Sedimentology of Upper Cretaceous and Tertiary
siliciclastics and coals in the Raton Basin, New Mexico and Colorado; in
Lucas, S. G., and Hunt, A. P., eds., Northeastern New Mexico: New
Mexico Geological Society Guidebook 38, p. 255-264.
Flores, R. M., and Bader, L. R., 1999, A summary of Tertiary coal resources of
the Raton Basin, Colorado and New Mexico; in 1999 Resource
assessment of selected Tertiary coal beds and zones in the northern
Rocky Mounntains and Great Plains region: U. S. Geological Survey,
Professional Paper 1625-A, Chapter SR.
Flores, R. M., and Pillmore, C. L., 1987, Tectonic control on alluvial
paleoarchiteture of the Cretaceous and Tertiary Raton Basin, Colorado
and New Mexico, in Ethridge, F. G., Flores, R. M., and Harvey, M. D.,
Recent Developments in Fluvial Sedimentology: Society of Economic
Paleontologists and Mineralogists, Special Publication 39, p. 311-320.
Flores, R. M., Roberts, S. B., and Perry, W. J., Jr., 1991, Evolution of Paleocene
depositional systems and coal basins in a tectonic continuum, Rocky
Mountain region: Geological Society of America, Abstracts with Programs,
Geological Society of America, v. 23, no. 4, p. 22.
Flores, R. M., and Tur, S. R., 1982, Characteristics of Deltaic Deposits in the
Cretaceous Pierre Shale, Trinidad Sandstone, and Vermejo Formation,
Raton Basin, Colorado: The Mountain Geologist, v. 19, no. 2, p. 25-40.
Appendix 2, page 3
Foster, R. W., 1966, Oil and gas exploration in Colfax County, in Northrup, S. A.
and Read, C. B., eds., Taos-Raton-Spanish Peaks country: New Mexico
Geological Society, Guidebook 17, p. 80-87.
Geldon, A. L., and Abbott, P. O., 1985, Selected climatological and hydrologic
data, Raton Basin, Huerfano and Las Animas Counties, Colorado, and
Colfax County, New Mexico: United States Geological Survey, Open File
Report 84-138, 268p.
Geldon, A. L., 1989, Ground-Water Hydrology of the Central Raton Basin,
Colorado and New Mexico: United States Geological Survey, Water
Supply Paper 2288, 81 p.
Grambling, J. A. and Dallmeyer, R. D., 1990, Proterozoic tectonic Evolution of
the Cimarron Mountains, north-central New Mexico, in Bauer, P. W.,
Lucas, S. G., Mawer, C. K., and McIntosh, W. C., eds., Tectonic
Development of the Southern Sangre de Cristo Mountains, New Mexico:
New Mexico Geological Society 41st Annual Field Conference Guidebook,
p. 161-170.
Grant, P. R., and Foster, R. W., 1989, Future Petroleum Provinces in New
Mexico-Discovering New Reserves (Atlas): New Mexico Bureau of Mines
and Mineral Resources, 94 pages.
Griffiths, S. A., 1981, Depositional Environments and Provenance of the Trinidad
Sandstone and Related Formations, Vermejo Park, New Mexico. [Master's
thesis]: Indiana University, 195 p.
Griggs, R. L., 1948, Geology and Ground-Water Resources of the Eastern Part
of Colfax County, New Mexico: New Mexico Bureau of Mines and Mineral
Resources, Ground Water Report 1, 182 p.
Haun, J. D., and Kent, H. C., 1965, Geologic history of the Rocky Mountain
region: Bulletin of the American Association of Petroleum Geologists, v.
49, no. 11, p. 1781-1800.
Hemborg, T. M., 1996, Raton Basin coalbed methane production picking up in
Colorado: Oil and Gas Journal, (Nov 11, 1996 issue), p. 101-102.
Hemborg, T. M., 1998, Spanish Peak Field, Las Animas County, Colorado:
Geologic Setting and Early Development of a Coalbed Methane Reservoir
in the Central Raton Basin: Colorado Geological Survey, Report 33, 34 p.
Hemmerich, M., 2001, Cenozoic denudation of the Raton Basin and vicinity,
northeastern New Mexico and southeastern Colorado, determined using
apatite fission-track thermochronology and sonic log analysis:
Appendix 2, page 4
Unpublished M. S. independent study, New Mexico Institute of Mining and
Technology, 121 p.
Hemmerich, M. J., and Kelley, S. A., 1999, Exhumation of the Raton Basin,
southeastern Colorado, determined from sonic long velocities: Geological
Society of America, Abstracts with Programs, v. 31, no. 7, p. 245.
Hoffman, G. K., 1996, Coal Resources of New Mexico: New Mexico Bureau of
Mines and Mineral Resources, Resource Map 20, scale 1:1,000,000, 22 p.
Hoffman, G. K., 1990, Coal geology and mining history in the Dawson area,
southeastern Raton coal field, New Mexico, in Bauer, P. W., Lucas, S. G.,
Mawer, C. K., and McIntosh, W. C., eds., Tectonic Development of the
Southern Sangre de Cristo Mountains, New Mexico: New Mexico
Geological Society 41st Annual Field Conference Guidebook, p. 397-403.
Hoffman, G. K., and Brister, B. S., 2003, New Mexico's Raton Basin coalbed
methane play: New Mexico Geology, v. 25, no. 4, p. 95-110.
Howard, J. D., 1969, Depositional controls of upper Cretaceous coal units: The
Mountain Geologist, v. 6, no. 3, p. 143-190.
Howard, W. B., 1982, The Hydrogeology of the Raton Basin, South-central
Colorado [Master's thesis]: Indiana University, 95 p.
Izett, G. A., and Pillmore, Charles L., 1985, Abrupt appearance of shocked quartz
at the Cretaceous-Tertiary boundary, Raton Basin, Colorado and New
Mexico: Geological Society of America, Abstracts with Programs, v. 17,
no. 7, p. 617.
Izett, G. A., 1987, The Cretaceous-Tertiary (K-T) boundary interval, Raton Basin,
Colorado and New Mexico, and its content of shock-metamorphosed
minerals; implications concerning the K-T boundary impact-extinction
theory: United States Geological Survey, Open File Report 87-606, 125 p.
Izett, G. A., 1990, The Cretaceous/Tertiary boundary interval, Raton Basin,
Colorado and New Mexico, and its content of shock-metamorphosed
minerals; Evidence relevant to the K/T boundary impact-extinction theory:
The Geological Society of America, Special Paper 249, 100 p.
Johnson, R. B., Dixon, G. H., and Wanek, A. A., 1966, Late Cretaceous and
Tertiary stratigraphy of the Raton Basin of New Mexico and Colorado, in
Northrup, S. A. and Read, C. B., eds., Taos-Raton-Spanish Peaks
country: New Mexico Geological Society, Guidebook 17, p. 88-98.
Johnson, R. B., and Roberts, A. E., 1960, Depositional environment of the coal-
Appendix 2, page 5
bearing formations of the Raton Mesa coal region, New Mexico and
Colorado: Oil and Gas Journal, v. 53, no. 33, p. 84-88.
Johnson, R. B. and Wood, G. H., Jr., 1956, Stratigraphy of Upper Cretaceous
and Tertiary rocks of Raton Basin, Colorado and New Mexico: Bulletin of
the American Association of Petroleum Geologists, v. 40, no. 4, p. 707721.
Johnson, R. C., and Finn, T. M., 2001 Potential for a basin-centered gas
accumulation in the Raton Basin, Colorado and New Mexico; in Nuccio, V.
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Jurich, D. and Adams, M. A., 1984, Geologic overview, coal, and coalbed
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Jurie, C. A., and Gechard, L. C., 1969, Colorado Raton basin: Mineral resources
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Kaiser Steel Corporation, 1976, Underground and surface operations at the York
Canyon mine; in Ewing, R. C., and Kues, B. S. (eds.), Vermejo Park,
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Kauffman, E. G., Powell, J., and Hatten, D. E, 1969, Cenomanian-Turonian
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Appendix 2, page 6
Krutak, P. R., 1996, Depositional Environments of Codell-Juana Lopez
Sandstones and Regional Structure and Stratigraphy of Cannon City and
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Colorado Geological Survey, Open File Report 96-4, 96 p.
Kuellmer, F. J., Kendrick, D. T., and Baker, L., 1987, Trace element distribution
in coals of the Menefee and Raton Formations of New Mexico: Geological
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Lee, W. T., 1917, Geology of the Raton Mesa and other regions in Colorado and
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Lee, W. T. a. K. F. H., 1917, Geology and Paleontology of the Raton Mesa and
other regions in Colorado and New Mexico: United States Geological
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354 p.
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Appendix 2, page 7
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77 p.
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Appendix 2, page 8
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261 p.
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Pillmore, C. L., 1991, Geology and Coal Resources of the Raton Coalfield, in
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Survey, Bulletin 1972, p. 45-68.
Pillmore, C. L., and Flores, R. M., 1984, Field guide an discussions of coal
deposits, depositional environments, and the Cretaceous-Tertiary
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Pillmore, C. L., and Flores, R. M., 1987, Stratigraphy and depositional
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Rigby, J. K., Jr., eds., The Cretaceous-Tertiary Boundary in San Juan and
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Society of America, Special Paper 209, p. 111-130.
Pillmore, C. L., and Hemborg, H. T., 2000, Field guide to the coalbed methane
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Pillmore, C. L., Kauffman, E. G., 1990, Cretaceous strata of the Raton Basin,
New Mexico and Colorado: AAPG Bulletin, v. 74, no. 8, p. 1341.
Appendix 2, page 9
Pillmore, C. L., Tschudy, R. H., Orth, C. J., and Gilmore, J. S., 1983, Stratigraphy
of the Cretaceous-Tertiary boundary in the southern Raton Basin, New
Mexico and Colorado: Abstracts with Programs-Geological Society of
America, v. 15, no. 5, p. 308.
Pillmore, C. L., Tschudy, R. H., Orth, C. J., Gilmore, J. S., and Knight, J. D.,
1984, Geoloogic framework of nonmarine Cretaceous-Tertiary boundary
sites, Raton Basin, New Mexico and Colorado: Science, v. 223, no. 4641,
p. 1180-1182.
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South Canadian River channel sands New Mexico, Texas, and Oklahoma:
The American Association of Petroleum Geologists Bulletin, v. 31, no. 1,
p. 15-37.
Pollastro, R. M. and Pillmore., C. L., 1987, Mineralogy and petrology of the
Cretaceous-Tertiary boundary clay bed and adjacent clay-rich rocks,
Raton Basin, New Mexico and Colorado: Journal of Sedimentary
Petrology, v. 57, no. 3, p. 456-466.
Rose, P. R., Everett, J. R. and Merin, I. S., 1984, Possible basin centered gas
accumulation, Raton Basin, southern Colorado: Oil and Gas Journal, v.
82, no. 40, p. 190-197.
Rose, P. R., Everett, J. R., and Merin, I. S., 1986, Potential basin-centered gas
accumulation in Cretaceous Trinidad Sandstone, Raton Basin, Colorado,
in Spencer, C. W. and Mast, R. F., eds., Geology of Tight Gas Reservoirs:
The American Association of Petroleum Geologists, Studies in Geology 24
p. 111-128.
Scafer, D. D., 1980, Thermal Alteration of Sandstones by Dikes and Sills in the
Raton Basin, Spanish Peaks Area, South-central Colorado [Master's
thesis]: University of Texas, 200 p.
Scott, G. R., Wilcox, R. E., and Mehnert, H. H., 1990, Geology of Volcanic and
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Appendix 2, page 12